http://www.realsg.com/2012/09/guide-borderlands-2-unique-and.html --- Incompetent good intentions will only bring tragedy. If you intend to do what is right, you need the strength to accompany that. -Kratos Aurion (ToS)
Most definitely farmable from bosses - it's kinda one of te points of the game :)
The want us farming bosses at least as much, if not more so, than farming chests.
That would be the whole point of an action-RPG, look at Diablo. Hell, the game even tells you so, literally one of the loading messages says you can go back to fight bosses over and over to get their best loot. Don't forget too odds for better gear will be better with more players, but make sure it's established who's getting what ahead of time... --- MapleHoodOG