Hydra Head has a good range of stuff on it, though thankfully it's not an Isis fan boy label. Southern Lord of course has all the Earth-worship bands. And there's NULLL records, mainly there to give an outting for Stijn van Cauter's music, but there's some other things on there. Mostly to the darker, more Droom side of things though.
It's impressive how quickly (most) Drone has evloved from it's roots in Earth into so man things. THose bands that are just crushing walls of Drone noise, to bands that take the Drone Doom Metal idea of Earth further, to ones that mix parts pure Drone with parts Doom to create more textured soundscapes. And lots of other stuff as well.
