I go through a lot of bands and albums, but certain albums have permanently glued themselves into my playlist for the better part of a decade.
Engine Down - Demure - http://www.youtube.com/watch?v=UmHY2wbaObc
To/Die/For - Jaded, Epilogue - http://www.youtube.com/watch?v=VdO6IsP-WY0
Katatonia - The Last Fair Deal Gone Down - http://www.youtube.com/watch?v=PxvjrowbN44
Newer stuff that I've had on repeat for the last several months:
Madder Mortem - Eight Ways - http://www.youtube.com/watch?v=CQ0AayHr8XU
The Provenance - Red Flags - http://www.youtube.com/watch?v=NZzsl_vSgzw
The Dear Hunter - Act III: Life And Death - http://www.youtube.com/watch?v=t0K2pxn62B0
All of that is various flavors of metal / goth-metal-type stuff EXCEPT:
Engine Down - old "emo"ish band that was doing that shit before it became the fucked up nu-goth bullshit it ended up being later on. In my opinion they're the spiritual successor to Sunny Day Real Estate, if you know who they are. Kinda different and not quite that low key, but in the same vein.
The Dear Hunter - I have no suitable classification for this band. It's like someone wrote some insane movie musical, released the soundtrack and then forgot to actually make the movie. Their stuff is all over the fucking place. Happy, sad, slow, fast, heavy, soft... and all that shit generally happens in just about every song on all their albums. The song I linked is pretty heavy, cause that's how I like it, but I could have just as easily linked to something like this http://www.youtube.com/watch?v=O_AgwXR1Los
@drewjmore: I played the hell out of Morning View when it was out. Haven't listened to it in a long time, but now that you mention it I think I'll dig it back up and throw it in for a while. I remember getting really pissed off at Incubus when one of their next albums was released (Murder of Crows or something?) and I hated every single song on it.
@Shackman: Here's some more 90's music for you 
And yeah, I've been really bored tonight...