I like Opeth but I disagree that their new material is weak. Watershed is nice and freaky, the moment near the end of "Burden" where the guitars go out of tune is just what I wanted to hear from the band. Their peak for me was definitely the first two albums which had great prominent bass, counterpoint guitar melodies, and bizarre song structures (usually taken to epic proportions with 10+ minute songs). I thought the general weirdness of the early band came back in some form in Watershed; it's got me back into them.
Fans of Mindless Self Indulgence should also check out Atari Teenage Riot if they haven't already, especially the album 1995 (alternatively called Delete Yourself).
Some albums I've gotten into lately from bands/artists that perhaps deserve more credit, in a variety of genres:
Crumbsuckers - Life of Dreams (crossover thrash, for fans of D.R.I.)
Tarwater - 11/6 12/10 (indie electronic, trip hop)
"????" (a.k.a. Four Question Marks, for those who want to search for the band) - Titan (if you've heard Meshuggah, you get the idea - these guys knock the speed and insanity up a notch)
Alchemist - Jar of Kingdom (psychedelic death metal!)
Carbonized - Screaming Machines (sounds like later Black Flag playing Voivod songs!)
Faxed Head - Uncomfortable but Free (lo-fi metal with an extra studio touch - reminds me of the early Butthole Surfers, but if you ask me this is even more out there)
Watchtower - Energetic Disassembly (the first technical thrash album! Hear if you're into Voivod)
Zoogz Rift - Idiots on the Miniature Golf Course (the heir to Captain Beefheart! There's a distinct Frank Zappa flavour to this music as well.)
The Jazz Composer's Orchestra - The Jazz Composer's Orchestra (free jazz with epic "experimental big band" arrangements! Cecil Taylor Unit fans would dig)
Spontaneous Music Ensemble - Karyobin (one of the great underrated milestones of improv music)
That's all for now, I'm afraid of going overboard here.