voltrader - 4:37 pm on Jul 15, 2005 (gmt 0)

Couple of things to add to the caveat about paid services:

- we did buy a service which included periodic updates, but the niche we were dealing with turned out to include many businesses in rural areas which tended to be undercovered. If you're starting with major metros, you probably won't have to worry about missing data.

- if I had to do it again, I would cross-ref the latest census data with the paid to try to plug holes.

- the big circle calc can be S - L - O - W if you're using a script to search thorugh the matrix of possibilities. Find ways to optimize it. A compiled plug-in?

Just thinking out loud...