Matching the exact grey will be difficult, so pick an area rug with some grey and other colors you might want to use as an accent. A style that fits your style, modern, will add a lot of color to the space, and also help in the choice of accessories.

it also really depends on your style - what are you looking to do with the room? whats your style? :)

Any colour that suites your fancy should work here. You almost "ignore" the mid-tone floor colours and work with the sofa/chair/pillow tones. Teal is being used very happily with grays and mid-tone brown (photos of sofa/chair and flooring would help). Your personal style will also dictate what colour you want to work with.

Personally I'm a fan of red so my choice would be a bold red carpet...but that's me. You need to decide what colours you REALLY LIKE and then go out and find them. There is something very satisfying about having a home that uses your favourite colours in your design.

Cancork is right - teals and cobalt blues are very popular right now! A medium tone floor means that you can use a darker rug without worrying about making your room too dark. (*Usually. We can't be 100% sure without a photo.) Purples, reds, and deep greens also work well.