The two I have chosen are MLS Companion Database for the PC or MAC and iPhone and Ward Tools for Windows Mobile, Palm, or iPhone. Both seem to still be well supported with keeping up to the export format from MLS and are Free open source programs.
Both programs have currently been upgraded to support MLS 3.1.1 to keep users going, but are also still being tweaked to take advantage of some of the new data in the MLS 3.1.1 exported csv files. It's still worth giving them a try during this upgrade time.
MLS Companion Database is a great tool for Bishoprics to help keep additional detailed information about ward members on their own PC along with being a really good reference tool for information without having to access MLS on the ward computer.

Ward Tools is also a great reference tool for leaders to access ward membership information on the go with the various hand-held devices we now use without having to access MLS on the ward computer.
