Does anyone know of a tool where I can feed in a list of (thousands of) domains and get the country in which they're hosted?

There used to be a set of opensourced geoip data.  We used to dump it in to mysql periodically for large lookups.  Not the most accurate, but not bad.  If that sounds useful I can see if I can find where we got it from.
Edit - just found it: http://www.maxmind.com/app/geoip_country

very useful, thanks