one problem right off the bat with dibs.net is that, as with seemingly 100% of US-based sites relying on geo-location information, it fails horribly outside of the (US-based) developer's market: I'm currently in Lucerne, central Switzerland, yet it put me in Emmen, a sleepy suburb north of Lucerne.

Edit: A quick re-test with the google map thingy shows me that dibs.net doesn't even want to know about Lucerne, and instead is fixated on suburbs and villages around Lucerne :(

My advice: Until there's some magical geolocation service that works 100% all of the time, don't offer it. I know I can change it on your site, but many many many people won't be doing that.