Very nice mashup with Twitter that has a clean, usable interface and good API for geocoding a location and even macros (so you can do things like L:home, L:work)
My name is Andrew Turner - a neogeographer involved in helping build the geospatial web. I am the CTO of FortiusOne, where we're building GeoCommons, a platform that makes it easy for people to build and share collaborative maps and customize their slice of the GeoWeb.