Flash Cards

http://www.cueflash.com
The web site states "cueFlash is a virtual flash card web program that you can access from anywhere. If you want to learn almost anything, from psychology terms to a foreign language you can learn it with cueFlash.
With cueFlash you can share decks with classmates, and add rich text to cards. When flipping through cards, the application continually resorts the deck to focus on cards you don't know."
View their demo video:
http://flash.screeniac.com/cueflash/cueflash.html?TB_iframe=true&height=675&width=1000