Utility to view request/response headers during browsing session?

I'm wondering if there are any utilities out there that will display the request/response headers sent/received by my web browser during a browsing session. Does anyone know of anyth开发者_开发知识库ing useful?

I'm familiar with the Modify Headers add-on for Firefox 4 and the HTTP Client utility for MacOSX but neither of these do quite what i'm looking for.

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I suspect Fiddler might help here - it captures all of the traffic, including headers, content, etc. It works on startup with IE or Chrome; Firefox needs to be configured to use it as a web proxy.