Color first. When I get my hair professionally cut and colored, they do the color first.

Color first. It changes the texture of your hair. If you can wait a couple days before the cut, the better, especially if you are lightening.

How much do you have to cut? On What Not to Wear, Nick generally does the color first, unless there's a lot of hair to cut off, in which case he does a rough cut, colors, and then finishes the cut.

yes absolutely colour first. That way the ends (which are often dried a bit by the colour process) can be snipped off / neatened up. Otherwise you might wind up looking a tad fuzzy.

Thanks all! I'm just covering some gray, not going too far off my natural shade. And my hair's fairly short already, so I'm just getting some (overdue) maintenance. I think I'll color it tomorrow night and get it cut Friday.

Color first, unless it's a major cut. If you were doing a lot there's no reason to dye a ton of hair you're chopping off (as someone who is usually just over the hair maximums for a single box of dye.)

My Mum's a hairdresser. She always reckons that the color builds up in the ends, as that is where the "combed-through" color ends up. If you color your hair regularly, the build up is noticeable: the ends are darker or more bleached, depending if you are darkening/lightening. So it is best to color then cut - this also reduces split ends (apparently).
Her logic is sometimes a bit tortuous (on sooo many topics). But she does have the experience to know about hair ... :-)