ServiceCapture - a good tool for any web application developer

ServiceCapture runs on your PC and captures all HTTP traffic sent from your browser. It is designed to help Rich Internet Application (RIA) developers in the debugging, analysis, and testing of their applications. ServiceCapture is the only tool of its kind to de-serialize and display all Flash Remoting or AMF traffic in an interface.

This is a nice tool with following features some of these are unique to this tool:-

I have just started to use it and yet to explore it completely. I, personally, feel that this could be very useful tool for Macromedia Flex application developers, as they have to deal with HTTPService/WebService/RemoteObject(AMF) quite often.
Good thing is that you can download the trial, use it for fifteen-days and if you find it useful, you can buy it.
Flex developers, don't forget FlexBuilder it also has similar capabilities except Bandwidth Simulation. You might want to compare the two before buying :)