EDIT: LiveHTTPHeaders version 0.13.1 is available!

LiveHTTPHeaders 0.12 seems to work fine with Firefox 2.0, but the maxversion 1.5+ tag in the install.rdf prevents it from installing.

Download LiveHTTPHeaders modified for Firefox 2.0 - I have modified only the version (0.12 => 0.12pda) and maxversion (1.5+ => 2.0+) in the install.rdf, nothing else is touched.