web development with safari?
this gives you colored source code, validation warnings, html manipulation, cookie management, information about images, stylesheets, scripts and http headers as well as a bunch of nifty features which actually doesn't belong in the field of web development -- but they are indeed very convenient.
brave os x users then get a nightly build of webkit to enjoy the web inspector (or find that it doesn't work unless safaristand is disabled again).
but it's wicked, nevertheless -- not just because sometimes firefox's huge memory footprint is simply not acceptable anymore.
firebug lite won't satisfy the blessed firefox user, though.