Even the cookies. It's been in webkit for a while. SO USEFUL.
You can also use it to leech stuff from login/captcha protected download areas like rapidshare or the apple dev center. No more failed browser downloads of 1gig files! Just add -C to your curl command!
Well Chrome had this feature for a long time. Personally I don't find it much useful. But to me the killer feature of firebug is that when you open an XHR entry in new tab it opens the tab with all POST variables. Super handy when debugging REST api.
You can also use it to leech stuff from login/captcha protected download areas like rapidshare or the apple dev center. No more failed browser downloads of 1gig files! Just add -C to your curl command!