Tether your phone with ICS/WMWifiRouter/Whatever you tether with and use this website:
http://www.dslreports.com/mspeed
It'll probably tell you the 100k test is too small, so just use the 400k or the 1MB test file. I'm not sure where the test server is located but it doesn't really matter; if everyone used the same speed test we could compare notes.