There's many I like. Here's just a few..
Slayers NEXT : Give a Reason (I recommend the Giga Mix version if you can find it)
Grenadier: OP theme, "Kohaku"
Chrno Crusade - end theme "Sayonara Solitaire"
Higurashi no Naku Koro ni : OP self-titled track, and the end theme, "Why, Or Why Not"
Bleach : "D-tecnoLife" (Second OP)
Fate/stay night - OP "Disillusion"
Naruto - end theme (12th) "Parade"
Black Lagoon - OP "Red Fraction"
The Melancholy of Haruhi Suzumiya : End theme - "Hare Hare Yukai"
Lucky Star - OP theme (Gotta wonder if this song will give "Hare Hare Yukai" a run for the money.... Perhaps even the dance as well? hmm...)