FMDB (Flying Meat Database) is an open source Cocoa wrapper for SQLite. It is maintained by Flying Meat Software, but is publicly available on GitHub (but don't expect any documentation!).
Original post by Gus Mueller announcing the move to Google Code: http://gusmueller.com/blog/archives/2008/06/new_home_for_fmdb.html
This has moved once again to GitHub:
You can download the source from github, or run the following command from Terminal.app (assuming you have git installed):
git clone http://github.com/ccgus/fmdb.git