Study Stack lets you easily create (after your register) flashcards, hangman games, word searches, and many more activities.
I had been less-than-impressed with it the first time I tried it quite awhile ago, but it seems to have added a lot of functionality. I’m adding it to The Best Sites For Making Crossword Puzzles & Hangman Games.
Thanks to a tip from Donna Murray, I checked it out again.
In terms of creating flashcards, however, I still think no one comes close to Proprofs. Their process is so easy, and you can quickly add images and videos to them, too.