I'm looking for bands (preferably with metal sensibilities) that use no guitars in their music. I currently have only the jazz-rock/fusion band Trioscapes in my collection that fits the criteria, but really any genre will do.

Om are trance-inducing stoner/doom with just drums/bass/vocals. There's a really awful brutal death metal band with no guitars, but their name escapes me at the moment.

How about the Power Metal sounding Van Canto? Aside from the use of drums, it's nothing but singing & vocal noises. They mostly just do covers.

Shrum feature dual bass guitars and no six strings. They play sludge/death metal. Cop Shoot Cop do the dual bass thing too, they played noise rock.

Violent Silence from Sweden. More prog than metal but really good.

Neoandertals.

That reminded me of Dead Neanderthals, I'm ffairly certain they are just drums and saxophone, they play free jazz/hardcore

www.youtube.com/watch?v=Xp1JTqQS_8M‎

Botanist?

Om and Apocalyptica are the first ones that come to mind.

http://www.metal-archives.com/bands/Om/33472
http://www.metal-archives.com/bands/Apocalyptica/1752

Profanum is the first band of this type (no guitars yet completely utterly metal)that I ever heard. And its the only one that's stood the test of time.
Profanum's Aeternum - Eminence of Satanic Imperial Art is essential BM listening from '97. Its quite unlike anything that was out at the time.
Dim the lights and enjoy this slice of darkness :

http://www.youtube.com/watch?v=pZ5ocbkgYCs

Necromantia, totally metal and using 2 basses instead of guitars. Check out Crossing the Fiery Path and Scarlet Evil Witching Black.

Barren Oak has become a recent favorite of mine.

Smoke and Smoke are a great band. "Do you think for a second that Smoke and Smoke give a mother fuck?!? Give a mother fuck!"

Skuldom have no guitar if you're after black metal

http://www.youtube.com/watch?v=ieClgbdgMt0 need to be signed in to view, for tits and stuff.

I remember there was a time when playing live the lady screaming would strum away at a guitar, but I doubt it was even plugged in.

Neoandertals: http://www.metal-archives.com/bands/Neoandertals/46293

(Brutal death metal with no guitar)

Tevana 3 don't use guitars...but they do use electric kantele, so maybe it still sounds too much like they're using guitars for your request?

A few recs from a variety of genres.

Defuntos Portuguese BM, just bass and drums.
http://www.youtube.com/watch?v=8cqH_eGhxEY

Noxagt Norwegian sludge/noisecore, bass, viola and drums (1st 2 albums only)
http://www.youtube.com/watch?v=EZ8bkMs2Zeg

Dianogah US post/math-rock, 2 basses and drums
http://www.youtube.com/watch?v=B_HXJpKupTI

Rothko UK ambient/post-rock, just 3 bassists
http://www.youtube.com/watch?v=AVHQap4nCQo
http://www.youtube.com/watch?v=jYIhaLRg2M4

This rules.

sounds like a really bad version of cause for effect

this band should really drop the death metal grunts

Nobody suggested Bassinvaders?
http://www.youtube.com/watch?v=LilA34dqcCk

Monolithian should fill your needs (stoner/doom with a hint of black metal in some places):
http://monolithiandoom.bandcamp.com/album/one

Radiation Blackbody, instrumental metalish stuff - http://radiationblackbody.bandcamp.com/

Neoandertals are great. If you listen ten seconds into a song of them and hate them already, their music is not for you. But if you see them as a challenging listen and try to get behind their idea, the music is very rewarding. I'd rather compare them (especially the later two albums) to free jazz than actual death metal although they superficially sound like it.
A similar band (which is also the lone one in the recommended bands section) is Enmity, although they have a guitar in their setup. Someone commented on youtube: "This is what all metal must sound like to people who hate metal." Their only album Illuminations Of Vile Engorgement is devoid of any melody and monotonous as well. However I rather see it as an experimental take on the death metal formula and the general idea behind death metal. You don't have to like it, but it is certainly more than just retards trying to be "br00tal". Oh, and the last song is an acoustic flamenco/jazz guitar piece.

Cause for Effect are also great, although the jazz elements are much more prominent in both the bass and the drum work than in Neoandertals albums.

I think you're overthinking it too much.

Actually, Enmity is ultra tight and they obviously can repeat what they're playing, so they know what they are doing. When you listen to the record three or four times it all starts to make sense. It just seems to be extremely chaotic and disjointed. The riffs are actually pretty catchy, the tone is something really unique and overall it is brutal as fuck.

There's Bell Witch. Only one bass, drums and vocals.

The black metal band Black Funeral released 2 albums featuring midi-styled keys in place of guitars, 2004's "Az-i-Dahak" and 2005's "Ordog." An interesting and unique approach for sure, but very repetitive and not much staying power, if ya know what i mean. still worth hearing:

http://grooveshark.com/s/Daevodata/4uOjJ0?src=5
http://grooveshark.com/s/Harbinger+Of+P ... Od0t?src=5

now if bass guitar is optional, Ride For Revenge are definitely worth checking out. its like Godflesh gone black metal. killer.

This Big Business album is primarily drums and bass and is fantastic. I think there might be a couple guitar parts sprinkled throughout but it's minimal - http://hydrahead.bandcamp.com/album/her ... waterworks

If you dig powerviolence at all then check out Water Torture too
http://www.youtube.com/watch?v=EFjXVGFvb6U

In a similar thread, someone recommended Pivixki, and I bought that one.
It's a piano+drums duo that plays something hard to describe, but it does resemble grindcore.

Seconding this. Massive band. Longing rules.