Check out Mindsnacks man. If you have Apple products that is. I cant personally vouch for it, but I have 2 or 3 friends using it to supplement there Japanese vocabulary and it worked well for us when went to Japan.
I started using it a while ago and I really liked it. I had to stop, however, until I could get a book on German grammar to help me along. It's excellent for memorizing words but there's no help at all with grammar. I had to stop the program a number of times to google things to find out why something was done one way for a word and not for another. I just recently got a book (Harrap's German Grammar though Stern and Bleiler's Essential German Grammar also looked good - both are inexpensive) and I plan on using it along with Rosetta Stone.
The price can definitely be a concern. I got it as a gift so I can't complain about content vs. price, but I'm not sure I'd be as happy with it if I had to pay for it myself. At the very least, buy yourself a dictionary, a book on German grammar and if you have an iPod Touch, an iPhone or an iPad, the German app by Mindsnacks is well worth the $5. In less than half an hour of playing the first level, I can count to 20 German as quickly I can in English. Also, try listening to German news/talk radio or watching German TV shows online and see if you can find any German music that you like. I listen to a lot of German music and between translating some of the songs (word for word, not using a quick translator) and just listening to them so many times, it quickly adds to your vocabulary and helps improve your pronunciations.