DigitalPoint.com. I stumbled upon this site one day way, way back in 2004 on SEOchat. A really nice set of tools for your site. Gives you some great data on ranking. More SEO related than anything else.

Google AdSense Sandbox
This tool will show you what Google AdSense ads will be displayed for any webpage on the Internet.

Back Link Tracking Tool
Track backlink fluctuations to your web pages historically.

Coop Ad Network
Free network of site owners to share advertising space.

DNS Zone Transfer
Handy little utility to quickly pull your DNS zone files from your name servers.

FileMaker Pro Web Digger
This utility allows you to dig into your web-based FileMaker Pro databases to check their security.

FileMaker Database Server Probe
This utility allows you to check your FileMaker database server to see what platform it’s running as well as what database files are being served.

Keyword Ranking Monitor
Track historical search engine result placement data for any keyword/URL combo you choose.

Keyword Suggestion Tool (my favorite!)
Quickly see which phrases are searched upon the most (for determining the best phrases to target for your website).

PageRank Toolbar For Mac
A widget to show PageRank for the site you are on.

Website To Country
Find the physical country that any website is in.

Yahoo! Web Rank Tool
This tool will show you what any website’s Yahoo! Web Rank is (without needing the Yahoo toolbar).