Flippity
Flippity easily turns any Google spreadsheet into flash cards, a badge creator, a spelling quiz, a memory game, a word search, and more. Teachers can use Flippity for a variety of purposes: to present to the class, to assess individual students, or to have students make their own creations.
Warning: There have been recent updates to Google Sheets that have interfered with the functioning of some activities in Flippity. Please read more about it here.