I'm currently looking into using MPix.com for my photography printing. I got a couple test prints from the before and they looked good. But I'm about to get some larger (11x14) prints made and am preparing some files to get 4x6 proofs first.
They have a 24 hour turnaround and have a great reputation. When I get my prints in I'll repost with a review of the results. They have good prices, many options for paper, and you can specifically select not to have them do any color adjustments (but I recommend calibrating to their profiles and getting a small test proof before doing this on large, more costly prints).
And by "many options" I mean you can get your work on greeting cards, 3D statuettes, even your paintings on the back of playing cards :)
But as far as more useful options, they can print on canvas, business and post cards, and have a book printing service that I'm also looking into for portfolios and such.
p.s. How cool would it be to divide a mountainscape matte by fore/mid/back ground layers and get the 3D statuettes (http://www.mpix.com/productsinfo.aspx?prod=13
) made for some room decor. I gotta try that :)