If you're thinking about taking on a project to map your unit's membership, be aware that in the (September) 2009 Tech Talk, Rich Farr mentioned that
If you put in the effort to map your ward, you may be duplicating something that the Church is getting ready to make available to you.We have out in a beta environment right now a new version of maps. As we put the mapping data, and overlay it with the mapping technologies that already exist, using the various providers and technologies, it enables members (especially in places that are more dispersed) to understand where the members are at. (Thanks to Atticus Ewig for the Unofficial Transcript)
If you just can't wait to get started on your project anyway, here's the list of resources.
Safeguarding Membership Data
Google Earth and Membership Data
Another Mapping Program (HPaulsen's WardMap)
Yet another Map-maker post
Tools for Making Ward Directories and Maps
Map Links on Membership Directory
MLS membership to Google Earth or Google Maps http://tech.lds.org/forum/showthread.php?t=549
Other Discussion About Mapping Membership Data
Standardizing MLS Addresses
MLS to GPS Georeferencing members info
Using Web Tools to Map the Members
Map Location of Members
Using Free Mapping API's for Meetinghouse Locator
Missionary SmartPhone/PDA Ideas
Open Source Mapping Project
Why isn't MLS using the U.S. National Grid?
Stake / Ward Bounadry GIS in Google Earth
If I've missed any you think should be on the list, let me know and I'm happy to add it.