Hey, I used these self-studying materials from online during my self-study.
If you like to know which level of German you're in on, and like organziation of material, you need to try IE Languages: http://www.ielanguages.com/German.html
If you are a visual learn, and focuses on vocabulary, use German flashcards. They have German words and sentences based on levels of beginner, intermediate, and advanced: http://www.german-flashcards.com/
If you focus on grammar, and like insightful grammar lessons, you must try this Georgia Southern University professor's site. It's also great, because it offers exercises for each lesson: http://class.georgiasouthern.edu/german/grammar/grammar.htm
My personal favorite are lessons from Deutsche Welle. It's more for young adults and teens, because the lessons are colorful and interactive. They also have a game (MIssion Europe) where you learn German, along with French and Polish, while you play: http://www.dw-world.de/dw/0,,2547,00.html
Email me if you want more online resources for your self-study.