A few weeks ago, I was in need of a free star icon, and for the life of me, I couldn't find one that was quite right. I scoured over the Internet, all the while noticing the perfect little star in my browser.
A couple of times, I Googled for Firefox icons, but I couldn't find them posted anywhere. Finally, I realized that if I just downloaded the source, I could easily find the icons, zip them up neatly, and post them for all to share.
So that's what I've done here. Behold the Firefox icons. These are organized more usefully in the actual Firefox source, but if you don't mind a little icon browsing, the attached zip should have all the icons you see in your browser.
PS - these are licensed under the following licenses: MPL 1.1/GPL 2.0/LGPL 2.1, and are copyright Mozilla.