What (spam) sites are at that IP address?
Here’s a handy way to check out what sites are associated with an IP address:
A2B has recently implemented ping blocking to reduce the volume of spam hitting their geotagged search engine. They publish a current list of blocked IP addresses, and you can also submit queries to see what sites have been seen recently at a given IP address.
Here’s the list of sites from an identified spam IP address (70.86.36.194). They also list the blogs associated with the IP address.
Many of the blocked sites are submitting 6000 to 8000 pings per day. A2B reduced their ping traffic from 27GB to 6GB daily by blocking the 112 top spam blog IP addresses turning up in their server logs.
The lookup service is a little similar to some of the reverse DNS services that are available (IP to domain name), but it appears to have a shorter time horizon. A quick check on some sites I know to be on shared hosting services only shows some of the sites that are at their respective IP addresses.
via SpamHuntress, see also comments there from Sam Critchely of A2B.