My favs OST Are from Ayashi No ceres , Air TV Rozen Maiden =) they are really Good!

OST eh ? Well, as it's done by Kaijura Yuuki, I will like it, fufufu... like Mai Hime OST, Noir OST, some song in Gundam Seed/Destiny, and a lot.
But for now, I really like Uninstall, Op of Bokura No.

Had to reply...o_0;;

DNAngel, Wolf's Rain, Tsubasa...and...Fullmetal Alchemist.

So, lots. xP I have 6 hours worth of danged OSTs.

Current favourite list~

Motteike! Sailor Fuku of Lucky Star, this song is very merry~
5 of Get Backers
Modokashii Sekai no Ue De from NHK ni Youkoso!
Nightmare from Jigoku Shoujo (Futakomori? I haven't watch the second season yet )
Parallel Days from Suzumiya Haruhi no Yuuutsu

My favorite anime OST would have to be Vampire Princess Miyu. I have a things for violins. The Ghost in the shell OST are also really good.

Velvet Underwold from Weiß Kreuz.

hmm.... .Hack//sign - yasashii yoake
naruto, gundam seed destiny,.....

Escaflowne Movie OST
Full Metal Panic! The Second Raid OST

i love all osts by kajiura yuki! (e.g. tsubasa chronicle, mai-hime, etc)

Cowboy Bebop! I love the soundtrack...and ummm, Escaflowne, and anything by Joe Hisaishi! Yaaay!

Fullmetal Alchemist, Inuyasha, Cardcaptor Sakura, Haruhi Suzumiya no Yuutsu, Naruto. But I only like some part of them.

Everything that Yoko Kanno touch

If I have to choose I give it to Noir, but anything that Yuki Kajiura is involved in works for me.

My favourite OSTs are from: Inuyasha, Wolf Rain, Initial d, Graymore, Terra he, Hai-Hime, Hellsing, Basilisk, Gankutsuou, Tsubasa Chronicle, Fruits Basket, Ouran High School Host Club, Full Metal Alchemist, X 1999, Gravitation and many more.

Spirited away OST, Inuyasha best of collections, Naruto, Sainkoku, Fate/Stay Night, and Bleach.

BLEACH as well as TMoHS, Naruto and Claymore are definitely some of my favourite "anime" soundtracks. also loved the OP song/video for Dokuro-chan...fu fu fu

Galaxy angles, its goofy and stupid yet catchy

my favorite is the hajime no ippo other is gunsword

I love OST's, it's like you're watching (well, rather hearing xD) the series even when you're just listening to the music :3

My fav at the moment is the Mononoke OST, awesome music, eerie and epic at the same time.
One of my all time favs is Inuyasha music, it makes a nice background atmosphere
And I listen to to the Mushishi OST while studying for my exams, because the music is very calm and doesn't distract me :3

I have some for...
LOVELESS
GUNDAM SEED
DEVIL MAY CRY
FINAL FATASY
ETC.. ^^

anything from yoko kanno, fiction junction, yuki kujiura, key, uematsu nobuo

For me it's very difficult... But the best of the best for me is Tsubasa Chronicles (yep, but the series sucks u.u)

Easily both the Air Gear OST's. Can't quite place the genre but a great set of music, all by the same artist but each song is great to get ya moving. Highly recommended.