SamSpade.org has a fantastic collection of tools for digging up everything from falsified IP addresses to browsing the web anonymously to checking traceroutes, running whois and reverse lookups and much more. The site's super-clean, minimalist layout may lead you to think that you're surfing the web in 1997, but the sophisticated tools really report some impressive stats (and do it fast).

The name's killer, too (Spade was originally a detective character created by Dashiell Hammett in the '20s and '30s).