After 4 or 5 false starts, I finally got the WRT to do wireless scanning all the way from home work. I took a trimet across portland for about 30 minutes.
A simple shell script issues a scan command every two seconds and saves the output to a text file. I copied the 1600+ text files off the WRT to a mac and sorted and counted the SSIDs. you can see the whole list here.
The top 6 SSIDs are, along with the number of times seen:
34 "wifitoolbox" 36 "CBSEAL" 39 "VeriLAN" 155 "www.personaltelco.net" 348 "Color Technology Inc." 356 "\x00"
www.personaltelco.net makes sense since thats the ESSID of the AP at home and Color Technology is where I work. I think the \x00 is a WPA AP thats also at work.
VeriLan and wifitoolbox are local area WISPs.