Professional Mastering Online?

[Megazoid]

I've been collabirating with another producer online producing some trance/house style music. While composing wise we have produced some top remixes, i am not the world's best at mastering (i dont have a sound treated room to start with...).

I am not 100% happy that everything is "mixed right" to bring out each element of the track's the way it should be done to be of "commercial" release standard.

I was considering getting our final mp3 files mastered via carrotcottage.com. Anyone had experience or can recommend any other people who could help us?

[Paulie Phonick]

XARC Mastering is another option, but I have never tried them (only know they exist).