First and foremost MA's 5ive's Continuum Research Project should be mentioned - Kyuss influenced psychedelic stoner/sludge doom metal. I think they're on a bit of a hiatus now though.
Warhorse - amazing. I hope they have another go at a reunion....
Cable - southern tinged heavy sludge/doom metal from CT. Think they recently broken up (again)... and I really don't see them coming back anytime soon.
Ogre - amazing heavy traditional doom with some 70's parts from ME, kind of like The Hidden Hand and Clutch.
Eldemur Krimm - another great heavy trad doom band from ME
We're All Gonna Die - hard rock/heavy doom from MA. They play around here pretty often, worth checking out.
Planet Gemini - trad doom, they have about 7 or so albums out but don't really get too much notice. not too sure if they ever play live. think they're around the Cap area though.
Heretic's Fork - slow southern tinged doom from RI
Presley - really atmospheric slightly psychedelic stoner instrumental from MA
Ichabod - ex-hardcore band setting down and playing some slow doomy stonerish metal from MA
Doomriders - heavy loud sludge/stoner band (has a member from Converge I think) from MA
Tides - heavy atmospheric hydrahead type sludge from MA and NY
Seemless - stonerish metalcore from MA. not really worth checking out unless you like bad hardcore/metalcore.
and of course if you didn't know... Scissorfight - rocky southern stoner from NH
Almost all of these bands have myspace pages or should, damn it. There's probably a shit load we're still missing too. You can also check out
http://www.traktor7.com/ - local label with some crust/stoner/doom/punk/heavy rock/etc, run by I believe the frontman of Milligram (RIP), and now he's in Raw Radar War.
Also a lot of these bands played at Sweet Leaf Fest, awesome stoner/sludge/doom, which was at Evo's in Lowell this past year, and I hope they do it again this year.