Tools

Looks like SQL Server 2008 has some Geospatial stuff that I could leverage to do some of this (Gawd I could have used this stuff back in 2003!). I've also been poking around at Bing and Mappoint, which have some pieces that I could use (but I don't see supporting what I need, as far as custom data goes - it's too limiting).

I'm also trying to figure out if Azure has any of this new stuff. At this point, it is my preference (and my hosting company only has SQL 2005).

Might be able to develop the rough grid stuff off of this:

• Equirectangular projection
• Universal Transverse Mercator coordinate system
• Maidenhead Locator System

The Maidenhead looks promising - smallest resolution is 3.5 x 3 miles - and the encoding (MM44NN55) would easily lend itself to very fast SQL lookups (Quick calc to convert lat/long to Maidenhead, and then could pick which pair to look at - so MM for the world-level grid, 44 for regional, NN national, and 55 for local).