No prob - actually not that much work. If you need to EVER get the skinny on IP's or DNS info, always start here:
http://www.dnsstuff.com
This place is where all the uber-geeks start when tracking down the cretins that p*ss away our time by having to figure out who they are.
On the stale DNS part - be sure to find out what your stats package is using to do the reverse DNS lookup and that it is getting frequently refreshed - it can cause you to get false URL info if the user of the actual IP address has changed (like to a new URL).