Geolocate source ip addresses.
This would be fine if Google (and others) didn't constantly mis-locate my home and work IPs. In fact, today, Google thinks that my office IPs are coming from the UK. My range is an old UUNet IP block, hasn't changed in 13 years, and whois (still) shows things properly registered to my physical address. In the past 12 months, Google has considered my office IPs to have been "in" Canada, California, UK, and Japan (should be NY state).
My home IP(s) (VZ FiOS) have had me in Virginia, Canada, and NJ in the same timeframe.
The problem doesn't seem to be limited to Google, either. www.elgato.com showed me their UK site this morning, too, but I can't be sure if they geolocated me by IP address, or by an AdWords session cookie. At the same time, cnn.com, apple.com, etc. see me where I should be, as do a few "what is my IP address" websites.
Anyone have any ideas how this whole geolocation thing actually works nowadays?