Textbooks:
please note: all these textbooks are in PDF form and copyrighted -- I'm happy to share them with you but please do NOT share them with any other people! Some have my name printed on them because I accessed them from the publisher site.
01- Kaleidoskop (on USB Stick) -- the most commonly used German 4 textbook at American colleges. The "Thema" chapters contain reading materials and vocabulary learning, while the "Kapitel" chapters are grammar-based. Unfortunately I can't find answer keys so you can certainly practice, but I don't have an easy way for you to check your work. If you do go on with German, there's a good chance you'll use this book or something similar. Do take a look especially at the reading articles in each "Thema" chapter.
02- Motive A1-A2-B1 (on USB Stick) -- a good German textbook from Germany; starts from A1 (beginning level) but goes all the way to B1, so the later chapters would be a good challenge for you.
03- Denk Mal (on USB Stick) -- the German 4 followup to our textbook from Vista Higher Learning. Has great reading material and grammar explanations, would be pretty easy to work through on your own.
04- Schritte Plus (on USB Stick) -- another popular series of textbooks used in language schools in Germany. I've included the A2 and B1 levels here since I don't think you need the very basic A1 level!
05- Handbuch zur Grammatik (on USB Stick) -- an excellent high-level reference and practice book for German grammar, we used this in German 5/6 when I taught higher levels, to make sure students had all the grammar foundations covered.
06- Menschen A2 (on USB Stick) -- the "Menschen" series is used by the Goethe Institut for their classes in Germany, unfortunately I only have the A2 level (which might be a little easy for you). If you like it but want the higher level, you can purchase it from Amazon (https://www.amazon.com/dp/3192119039/).
07- German Vocabulary (on USB Stick) -- I've never used this, but for pure practice on vocabulary topics, it looks quite good!
08- Practice Makes Perfect Vocabulary (on USB Stick) -- three different books, focusing on grammar, verbs, and conversational structures to practice with
09- German for Reading Knowledge (on USB Stick) -- some higher-level reading practice would be good for you; the focus here is on reading only, without worrying about conversational skills or pronunciation, but it is a good textbook for that purpose
10- Schaum's Outline of German Grammar (on USB Stick) -- similar to the Handbuch zur Grammatik, this is a comprehensive overview that should answer any grammar questions you run into
Reading (Fiction etc):
https://gutenberg.spiegel.de/buch/die-schonsten-kinder-und-hausmarchen-6248/1 -- Projekt Gutenberg's copies of Grimm's Fairy Tales, or use the index to find MANY other old out-of-copyright German books
https://nosologoethevlc.files.wordpress.com/2013/03/kc3a4stner-erich-emil-und-die-detektive.pdf -- Emil und die Detektive is a 1930s book that might be really fun to read, it is often used in college classes for German reading
http://www.zeno.org/Literatur -- Zeno.org also has nicely-formatted text versions of older books
https://www.ebook.de/de/category/61018/ebook_de_edition.html -- has free ebooks, but you do have to create an account there
https://www.deutsch-perfekt.com/ -- Deutsch Perfekt is an online magazine meant for German learners, probably about the level you want
https://www.br.de/kinder/index.html -- Bavarian Radio Page for kids, includes articles and news targeted toward a young audience, might be a good level for you
https://www.dw.com/de/themen/s-9077 -- Deutsche Welle news site, a little advanced but if you can read news in German or at least struggle through it, you'd be in very good shape!
https://www.amazon.de/ -- you can buy books from Germany, the shipping costs a little more but it's not too bad really; I could recommend Tintenherz (https://www.amazon.de/Tintenherz-Cornelia-Funke/dp/3841500129/) or translations of books you already know like Harry Potter (https://www.amazon.de/Harry-Potter-Stein-Weisen/dp/3551317259/) or whatever you're interested in
Podcasts and Listening:
https://radiolingua.com/category/coffee-break-german/page/6/ -- Coffee Break German is a podcast with both very easy topics (the actual "Coffee Break German" series) or the much more advanced "CBG Mag" which is more B1-B2 level.
https://slowgerman.com/inhaltsverzeichnis/ -- Slow German Podcast is a good podcast for your level, with slowly spoken audio on many different topics
https://www.stitcher.com/podcast/bayerischer-rundfunk-2/do-re-mikro-die-musiksendung-fur-kinder-brklassik -- Do Re Mikro, a podcast from Bavarian Radio, is aimed at kids and teaches about music history, I really enjoyed parts of it and it's about the right level for you, so I've included some on the USB stick
https://www.dw.com/de/deutsch-lernen/nachrichten/s-8030 -- Langsam gesprochene Nachrichten is from Deutsche Welle, headlines and short reports of daily news in very slowly spoken German
https://www.stitcher.com/podcast/ndr-info-kindernachrichten -- Kindernachrichten, News for Kids in slightly easier-to-understand forms
https://www.dw.com/de/deutsch-lernen/alltagsdeutsch/s-9214 -- Alltagsdeutsch is a series for more advanced learners, but it might be good for you
https://www.stitcher.com/podcast/betthupferl -- Betthupferl, Gute Nacht Geschichten für Kinder are bedtime stories for kids in German
https://www.stitcher.com/podcast/kiraka-kinderhorspiele-im-wdr -- Children's Radio Plays from the WDR, West German Radio broadcasters; I've included some on the USB stick
Märchen (on USB stick) -- I've included some fairy tales and other audio stories/podcasts from various sources on the USB stick
Video Series:
https://www.youtube.com/watch?v=4-eDoThe6qo -- Nicos Weg whole series, part two is here: https://www.youtube.com/watch?v=Lg5P2w_Ro1c and part three here: https://www.youtube.com/watch?v=LkufozluseI but I've also included those on the USB stick
https://www.dw.com/de/deutsch-lernen/das-deutschlandlabor/s-32379 -- Das Deutschlandlabor is a great series in German on German culture, it can also be found on YouTube here: https://www.youtube.com/playlist?list=PLs7zUO7VPyJ50sTVsDgfJV6_B3rFYtbFu
https://www.goethe.de/prj/mwd/de/deu/mse/anl.html -- Mein Weg nach Deutschland is a nice short mini-series, I've included the first season episodes on the USB stick
https://www.youtube.com/playlist?list=PLs7zUO7VPyJ5q8vaO9vohSzNntbYvItJR -- Jojo sucht das Glück is a moderately-advanced video series
https://www.youtube.com/playlist?list=PLs7zUO7VPyJ4d4Qrm14DUNGjW0TX_LXQn -- Ticket nach Berlin is another series, I don't know much about this one
https://www.youtube.com/playlist?list=PL3936178A38BB5F87 -- Easy German focuses on interviews on the street with native Germans, is a great way to hear regular spoken conversational German (with subtitles)
https://www.bbc.co.uk/bitesize/subjects/z8j2tfr -- BBC has some good learning videos and online exercises, I've included the old "Deutsch Plus" video series on the USB stick
https://www.dw.com/de/deutsch-lernen/video-thema/s-12165 -- Video-Thema is pretty advanced, but if you can work through understanding these, you're in great shape!
https://www.youtube.com/playlist?list=PL5D443A49838608D1 -- BookBox German Stories for Kids -- might be TOO easy for your level!
https://www.youtube.com/user/SesamstrasseNDR -- Sesamstraße, Sesame Street in German
https://www.ardmediathek.de/ard/ -- the ARD Mediathek is the streaming library of the public Channel 1 in Germany; some shows are location-blocked but you can watch many of them online from the USA
https://www.zdf.de/sendungen-a-z -- the ZDF Mediathek is the streaming library of Channel 2 in Germany, some are location-blocked but you can watch many from the USA
Online Courses:
http://harry.dw.com/landing/en/ -- Deutsche Welle's "Harry, Gefangen in der Zeit" is an interactive video game series designed to help learn German. Some students have enjoyed it, I haven't actually used it much myself. You'll need to create a free account there.
http://deutschkurse.dw.com/KursPlattform/WebObjects/KursPlattform.woa/wo/2.1 -- Deutsche Welle's "Deutsch Interaktiv" courses, you'll need to create a free account by clicking on "New User" there.
https://learngerman.dw.com/en/overview -- Deutsche Welle's "German on the Go" uses the "Nicos Weg" video and has quick quizzes and other study materials.
https://deutsch.vhs-lernportal.de/wws/9.php -- VHS-Lernportal has A1-A2-B1 courses designed by the community college system in Germany (Volkshochschule = VHS). You will to create a free account to progress through the courses; I'd recommend starting with A2 (mostly review) or B1 (a bit of a challenge).
https://www.dw.com/en/learn-german/deutschtrainer-lektionen/s-32897 -- Deutsche Welle's "Deutschtrainer" focuses on vocabulary rather than grammar, but could be useful for expanding your vocabulary knowledge!
https://www.goethe.de/prj/dfd/en/home.cfm -- Deutsch für Dich is by the Goethe Institut, there are some good courses and exercises there
https://www.dw.com/en/learn-german/mission-berlin-episodes/s-9837 -- Mission Berlin is a video and game series designed to teach German, I've never used it but it sounds fun
Local Get-Togethers:
https://www.meetup.com/Deutscher-Stammtisch-San-Diego-North-County/ -- North County German Stammtisch meets twice a month, a gathering of both native and learning German speakers to socialize and practice German. They're very friendly, I went two or three times and found it quite pleasant, no pressure but a nice group of people.
https://www.meetup.com/german4fun -- a similar group of German learners but I don't know much about this one