It's more useful if you also know about/use http://www.ontok.com/ and http://www.alouie.com/geocoder/ (there's other geocoders out there on the web, but I found that these two were far better than the others I tried--they, between them, actually found all the addresses I wanted to look up).
For an example of what it can do, have a look at this:
http://www.tagzania.com/user/sj/sonoma-spotlight-on-ports?map=1&ndx=1
BTW ... what to do if you have an awful lot of jell-o (Jelly, for non-Americans like me), a light table and far too much free time (craziness courtesy of
wendelina2):http://www.lizhickok.com/assets/portfolio/pages/01city.html