Written to be fast and simple, but with all the features I personally wanted for running through my own sets of cards. Tag each card as "Known" or "Needs Work" and generate a custom quiz based on these. You can additionally filter a set based on how many times you have answered correctly (or incorrectly) any given question.
Flash cards can be created inside the application itself. However, entering lots of cards on phone keyboard is a pain, so the app supports two other ways for getting your flash cards into the app. The first is to use the Flash Card Generator:
The second way is to save your flash cards in an XML file and import those via the import screen in the app. If that is something you are interested, see this LINK for a description of the file format.
Once imported, cards can be updated on the device itself.