If you browse through the Google Docs Template Gallery you will find a bunch of templates for creating flashcards in Google Spreadsheets. There is also a flashcard script available in the script gallery (open the insert menu in a spreadsheet to search for the script). None of those templates nor the script is as easy to use as Flippity.

Flippity is a free tool for creating flashcards from data in a Google Spreadsheet. Flippity provides clear directions for the simple steps to take to create your flashcards. To create your flashcards use the Flippity template, enter your data, publish the spreadsheet to the web, then grab your Flippity link. Your Flippity link will take you to a Flippity page on which you and your students can flip through your flashcards. Flippity includes a shuffle function and an option to remove cards from your deck of flashcards as you flip through them.

Applications for Education
Flippity is a good tool that you and or your students can use to create flashcards for any number of topics. I learned about Flippity from Steve Fortna who is a Spanish teacher.