A new twist on the Craigslist housing mashup - Matthew Hill has added a new dimension to the Craigslist housing mashup UI. After selecting a city on JoLocate.com you're met with a jigsaw puzzle of the areas for that city. When you click one of these regions, listings can be sorted within that area by when they were added (Today, Yesterday or 2-6 days ago). Kind of a nice way to get an idea of how fresh a listing is.
RoadPetition lets you make your case by map - From the site: "..Use this site to find that annoying traffic light, stop sign, roadway, or intersection and make people aware of the problem! Leave a comment or just rate the location. Even create a petition or sign one if it already exists."
HoustonTexasRealEstate Map - Browse housing listings by neighborhood (Look to the bottom of the page for the map)
..These above real estate mashups would make for great My Maps content!