Don't really get into this area, but I like Orbital's "middle of nowhere" which was released a couple years ago. Solid album from start to finish, no filler. Ambient and trance can overlap, I guess Orbital is in both catagories. Aphex Twin is the big player here but I don't care for his stuff.
Best Ambient Music
Who's your favorite "Ambient" musicians. Patrick O'hearn is a favorite