Good ideas but there are issues with this approach. But to explain them here would probably cause me to run out of characters and bore 99% of HN readers. But you're absolutely right that some of these sources could help augment the accuracy of any IP geotargeting system. Unfortunately this type of data has been hard to get a hold of because of either privacy policy issues or some strange beliefe that this was proprietary/trade secret information.

Trust me, I've tried this in the past and came up empty most of the time. That said, it is a really good idea.