I haven't tried this app, and it is probably next to useless, but it seems very cool none the less (in an extremely geeky sort of way):
http://www.eddiem.com/nerds/tiki-ind...?page=Sonar+CE
I'd try it, but I'm at work. And even though the office is fairly empty the day after Christmas, I don't want to be walking around with my phone making loud chirping noises : )