This is useful: sitonomy.com (via J-Walk). For example, if you point it here, it tells you that I use Blogger for publishing, several web stats packages, and the Apache web server software. It will also identify widgets, affiliate programs, ad networks, web feed processors like FeedBurner, programming languages, content delivery networks, and so on if it can find them.
You can also point it to any individual page URL, so you can see what's different about my top headphone albums page: I have Amazon affiliate links and AdSense ads there, but not on the home page.
It's not as detailed in its specifics as, say, the Netcraft server query form (which will tell you my server software changes since 2002), but there's a lot more information at Sitonomy overall.
Labels: geekery, software, web