ChemWiki

I found a great resource through UC Davis: http://chemwiki.ucdavis.edu/

It's a wikipedia-like website that's incredibly easy to navigate. Not only does it have organic chemistry information, it also has sections in general chemistry (for those of us reviewing for the MCATs). Sometimes learning from an alternative source helps me studying, and this is a great one. It color-codes reactions so your eyes don't get tired looking at them. Here's a sample from their alcohol hydration page:

http://chemwiki.ucdavis.edu/Organic_Chemistry/Alcohols/Electrophilic_Hydration#Mechanism_for_3.c2.ba_Alcohol_(1.c2.ba_and_2.c2.ba_function_the_same_way).3a

I think the coolest part about this website is that they're developing a gaming system that helps students do practice problems. According to the SARIS website, students will be able to track which parts of problems they get wrong so they study more effectively. When a student gets a question right, they get "XP", a point system that allows them to level up in the game. Cheesy as it sounds, I could definitely see myself playing for practice - and points. I'm competitive! Here's the link if you want to read more:

http://chemwiki.ucdavis.edu/uSARIS

Hope this helps!