If you are looking for crowd-sourced localized frequency information, check out http://www.radioreference.com

Looking at the archive link posted in the other comment, this wiki was about identifying signals based on recordings, rather than location and frequency. Unfortunately the wiki is still down.

Site seems down, I found a cached version at archive.org: https://web.archive.org/web/20150905234615/http://www.sigidw...

It's a shame the site is still down; there's a lot of fascinating info on there. Some of the over-the-horizon radar samples sound like dubstep basslines.