Are you a googledocs user? You'll love this!
Yes, you can use Google Docs templates to create your flash cards (https://docs.google.com/templates?q=flashcards&sort=user&view=public) but flippity is so easy, you might want to skip all the templates and give it a try. Clean interface, the ability to put in images, shuffle, randomize - it's all here. Changing a card stack is as simple as republishing your spreadsheet after you make any additions. It even comes with a QR code so kids can access the stack from the projector. Brilliant. Try it.
(Here's a sample.)