Somebody referred me to the excellent Tamper Data extension today. Tamper Data can be used to track and modify http(s) requests ala live headers, but with a better feature-set. It has quickly become a new favorite for quick & dirty HTTP interception. It’s also got a few nifty features like various actions that can be taken on form fields. Go ahead, take a look. You might be pleased. It’s a decent alternative to all those memory-hogging java proxies out there… Thanks for the link, Dave.
In addition, here’s an interesting presentation about Web Development and Testing with Firefox that I just came across while looking up some of the links above.