Wow, to narrow it down to one, I'ld have to say B*tches Brew by Miles Davis. I hae to say that every time I listen to this album I find something new. There's some little thing that comes to my attention...and it leads me along to something else that I hadn't noticed. I must have literaly listend to it in it's intirity over a hundred times, and I still find something more in it.
However, I've realy been getting into UNKLE and DJ Shadow's Private Press has been getting a LOT of time on my system.