Lots of great names in this inspiring thread.
Trent Reznor is one of my big inspirations for working with sound. He has done so much great work with Nine Inch Nails and now he's done the score to the new David Fincher film, The Social Network - really looking forward to that one.
Another great modern producer is Dave Fridmann who has done beautiful work with Mercury Rev and The Flaming Lips. I once visited him in his studio in upstate NY and he's got a whole house that's constructed as a studio - The Flaming Lips usually records their vocals in the bathroom! The inventive sonics on all of his productions are really something - besides the aforementioned bands, also check out his work on the Low-album Drums and Guns, it's an amazing headphone experience.
These days, a new record I really adore is the latest album by Neil Young which has the beautiful title Le Noise. It was produced by another sonic master, Daniel Lanois, who has some very interesting thoughts on the record and on sound generally - check out this link: http://www.youtube.com/watch?v=qrbp9Tv9tHw
I also need to mention Brian Eno and Howie B as two sources of inspiration. But there's so much great stuff out there and a lot of the names mentioned in earlier posts on this page are amazing!