I couldn't find a Secret Santa app that didn't add all kinds of extra steps, like having each user register, so I created my own!
Add any number of names to a group. Name Drop will assign a gift name for each group member.
Press and hold to delete a name. This will also wipe out the assignments list.
It also includes the ability to save the most recent names and assignments and load them again. Once loaded, you can even re-assign the names again!