A great and addictive game with multiple possible playthroughs, Deus Ex also has a great atmospheric soundtrack to go along with it. You can find it here: KHInsider.
The OST is very subdued and gives a perfection background track for roaming the streets and doing missions. It's bombastic and sweeping when it needs to be, at dramatic moments in the game.
All in all not a OST for very active listening, but makes for a good background track.