I was catching up on some articles from Lifehacker, and they reviewed Cramberry.
It is free with registration, and it gives the user the ability to go in and create lists/sets, and it creates flash cards.
These card sets can be shared with other registered users (it just shows up in their sets as if it were their own).
I highly recommend people signing up to the daily Lifehacker Feed. They have TONS of stuff that they review, much of which is free and they come up with wacky ways to do every day things, again usually on the cheap of free. (http://www.lifehacker.com) or via feed (http://lifehacker.com/index.xml - add this to your RSS Feed reader)