Snoopy is a bookmarklet for snooping on web pages. It's intended for use on mobile browsers (such as Mobile Safari on the iPad) where you can't view-source to poke around under the hood of sites to see how they're built. You might find it useful for your desktop browser, too. Mark Perkins
Discovered this excellent solution while helping a friend solve a CSS problem with his web site. We were at the client office and unable to access his site due to the client's web filter restrictions. So we pulled up his web site on my iPad but couldn't view the source to see what might be causing the issue. Snoopy helped a great deal.