Oh this is pretty (also pretty useful):
If you click on the graphic above, Robtex will show you all sorts of useful information about your IP address (or any other you care to mention). The self-styled "swiss army knife internet tool" moniker is very apt.
I particularly love the graphical DNS graph if you type in a hostname. DNSBL aggregation is good too.
Better than DNSstuff. Recommended.
Hat tip: AntiSpamBloke (you know who you are).