AQA Biology Revision

Please help!
I am currently constructing a web site which will be a revision aid for students studying AQA AS biology. If anybody has any ideas on how i can make this site as beneficial as possible for the students, i would love to hear from you! Should it have revision tips, discussion forums?What would have helped you? If you use a web site at the moment for revision let me know why that particular site is good or bad.