Pretty much anything by Jesper Kyd (
Assassin's Creed &
Hitman soundtracks in particular). He composes a wide variety of music, invoking numerous feelings and setting a near limitless array of scenes, yet his music is very recognisable and consistent. The
Assassin's Creed II OST is probably the best example of Mr. Kyd's musical diversity.
The
Prince of Persia trilogy (the
SoT one) have some memorable tracks, although the 2nd game is more heavy metal-based.
In addition to the action genre is the
Devil May Cry soundtracks (
DMC4 in particular). Not very "dreamy" music (except maybe
Out of Darkness) but the fight tracks get the adrenaline pumping & make you feel like a badarse. And they're surprisingly catchy.
On the other end of the spectrum,
Mirror's Edge has some very nice 'astral/crystalline' atmospheric music. Those are the only words I can think of to describe it, but it's very pleasant.
Of course you can't overlook anime music.
Hellsing (TV series) has got some of the coolest, most universally-liked music I've ever heard, dipping into the "groovy" genres such as jazz (acid jazz in particular), classic rock and occasionally some nice synthesised tracks.
Hellsing: Ultimate (ongoing OVA series) has got some truly epic music as well, with bombastic pieces performed by the Warsaw symphony orchestra and some other battle-heavy 'modern' tracks.
Also, check out E.S. Posthumus. If "FUCKING EPIC!" was a music genre, they'd set the standards for sure.