Coil (on Brainwashed.com)
Coil are a fascinating band, of whom I've been a fan for a long time. One of the first wave of "post-industrial" bands after the collapse of Throbbing Gristle (of whom Coil member Peter Christopherson was a member), before the term industrial was redefined to mean the more commercially accessible genre it's usually taken to mean now. It's difficult to describe their music because it changes so much from one album to the next, but it's heavily experimental, mostly fairly dark in flavour, and deals with certain recurring themes of magic and paganism, gay sexuality, S&M and death. Not necessarily easy listening, though it can sometimes be quite beautiful, but definitely challenging and thought-provoking. Brainwashed.com is an umbrella site for variety of interesting bands and record labels, and even though Coil now have their own site outside of Brainwashed, I think this was the first. News, a detailed discography of both official Coil releases and side projects, MP3 samples, reviews and interviews, photos and more.
Coil - Threshold House
This is Coil's own site. It actually has considerably less information than the Brainwashed.com Coil site, but it's a very interesting visit anyway. The design is decidedly cutting edge, or perhaps bleeding edge might be a better term since it employs what some designers I know call "mystery meat navigation" and doesn't always work reliably. But it's lovely to look at and has some unique features like a pop-up "John Balance Automated State Monitor" (John Balance is Coil's brilliant but somewhat unstable lead singer who's been in and out of rehab many times and was recently hospitalized with a heart attack). The states listed (good, bad, tormented, elsewhere, and sleeping, plus possibly more that I just haven't seen yet) seem to change rapidly enough that I suspect it's actually random...
Current 93 - Brainwashed.com
Another difficult-to-describe-or-categorize band who come out of the same general milieu as Coil and have occasionally collaborated with them. As the name Current 93 indicates, there's a marked thelemic influence, particularly in their earlier work - they seem to have tired of it later, though spirituality of one sort or another seems a constant in their work. Current 93's sound ranges from noisy and abrasive (mostly their earliest work) to melodic and trance-inducing (like most of Island) to something that's been termed "death folk", and occasionally even gets extremely silly ("Crowleymass"). It can be beautiful, disturbing, depressing and humourous, sometimes all at once. One of my enduring favourites, since the mid 80s.
Negativland are probably better known for getting sued by U2 than for their actual music. A number of years ago they did a very irreverent (and unauthorized) cover/parody of U2's "I Still Haven't Found What I'm Looking For", which was absolutely hilarious but unfortunately caused them endless legal troubles. Negativland prefer to be known as an "experimental music and art collective" rather than a band as such, and their audio recordings are mostly tape collages that stretch the definition of "music" pretty far, but can be brilliant, insightful, biting and frequently quite funny as well. The site has a lot of interesting info on the topic of intellectual property rights, copyright and the legitimacy of collage as an art form as well. Side note: Negativland are also the inventors of the term "culture jamming", later made famous by Kalle Lasn and Adbusters.
A bit of a change of pace from the other artists listed in this category! But my feeling has always been that you can find innovators and original voices in virtually any genre of music. Buffy Sainte-Marie is a Cree singer-songwriter and activist, many of whose songs were banned in the 60s for their political content. Over the years she's moved away from folk and more into electronic music, and is also becoming known as a digital artist and multimedia producer as well. She's also still very much involved in Native issues, and in particular in using technology and new media to help Native communities.
The Gray Field Recordings
Official site for the experimental band The Gray Field Recordings. Intriguing and very hard to categorize -- the music is melodic and challenging at the same time, and often quite haunting, a bit reminiscent of some of Coil and Current 93's more accessible work. Includes several downloadable MP3s.