Nadja and more angelic process are all on my to-listen list for this already. Any thoughts or suggestions for additional listening in this vein?
I honestly don't see why you need to listen to more then that. Easily the best two bands ever- TAP in particular is miles ahead of any other band as far as totally awesome music goes. Check my reviews on Nadja on Metal-Archives for suggestions if you want, I've reviewed almost every single release of theirs on it. Buy every single Angelic Process release straight off, you won't regret it.
Seconding OWW's Growing (I think they are a bit overrated but yet I keep on listening to them). Bardo Pond is also a very good idea, a bit more stonery and a bit less shoegazey but still extremely good times.
I would liken Tim Hecker's approach as jesu or Isis within an ambient context, well worth checking out.
The Goslings have an extremely loud (quite fatiguing, actually) sound, I liken it as MBV and Boris and an absolutely massive amount of tape distortion. Grandeur of Hair is pretty cool, as is Occaison. Something you must hear, this, and I'm honestly surprised that no one here has mentioned them.
Seconding Thergothon, that's some seriously epic funeral doom stuff right there. Not remotely shoegazey or anything, but very slow, very heavy and imbued with a strange sense of grace and elegance. Essential.
I think some later Godflesh could fit this thread, too. Hymns is still fairly industrial-ish but quite uplifting, very solid stuff indeed.
For epic trance inducing drone, check out Burial Chamber Trio, particularly Side B.
Li Jianhong does some excellent, albeit quite noisy, one man guitar stuff that vaguely reminds me of TAP for some reason (just not as mind blowingly good, naturaly). Don't know how easy it is to find, but get San Sheng Hi.
Finally, I'm surprised OWW didn't mention Alasehir (think he was the one who uploaded that). Very jammy and psychedelic, really awesome stuff.
Also, tell us what out of here you liked/disliked the most out of the recs so far. No point listing off another 50 or so bands.