With pubDB, you can find traffic stats of websites. Pub-db.com also maintains a database of adsense/ google-analytics publisher ids to identify website networks and ownership. Furthermore, you can lookup miscellaneous information on a domain - ip address, server location, websites hosted on the same ip and more. You can also use pubDB to estimate the value/ worth of your website.
2919842 websites and counting...
Spy: Adsense Id Lookup | Google Analytics Code Lookup
Tools: whats my ip, host by name, host by ip, reverse ip