I can't believe this is the first time I've run across it but Fiddler 2 is available. And it's been out since September last year!

Fiddler for those not in the know Fiddler is a debugging proxy you can use for examining what is going on when you hit a web page. It's very cool stuff (especially with all the new bits in it) but I can't help wondering what genius thought releasing version 2 under a completely different url was a good idea, and then not linking to it from the main Version 1.x site!