Another vote for Melvins - awesome.
If anyone is into Alt. Jazz you should check out a british band called Acoustic Ladyland and their slightly mellower sibling Polar Bear, they are simply incredible and great live. Almost, dare I say it, Punk Jazz...
Other bands I'm listening to a lot at the moment are Discordance Axis, Mastadon, Soilent Green, Mistress, Boris, High On Fire, Charles Mingus and other stuff along those lines...