The lovely thing about a hallway is that you can really go to town (see also bathrooms) as you don't spend much time in there. Is your hallway dark or light? General rule is: if it's dark, go for dark paint; if it's light, go for lighter paint.
Another thing worth thinking about is the rooms that lead off the hall, and what other walls you can see as you move through the hall. I like quite strong colours in my rooms, but the hallway and stairs are white as I like that contrast, that sense of stepping from a light and airy space into a jewel box (ooh get me). The other way round works too: dark dramatic hallway leading to pale/neutral rooms.
The colours that are occurring to me are a bit random, because of course I don't know your taste or what the rest of your house looks like, and also I'm going to suggest posh paint which you can look at online, though of course you can buy cheaper alternatives:
So first, how about a blue/green/grey? I like Farrow & Ball's Oval Room Blue, or a paler choice would be Light Blue (which has a greeny sludgy tone). I've just painted a wall in Mylands Shoreditch, which is a green grey that changes tone throughout the day (green in the morning, grey in the afternoon, blue at night!). Mylands also does a colour called Mid Wedgwood which I haven't tried, but looks lovely: a blue-grey.
If you want to stay neutral, I'd stay away from pale grey because I think it might be a bit drab with the flooring. Go for a dramatic grey, then brighten the walls by hanging pictures in matching frames (black, gold, silver, or a strong colour). Paint & Paper Library has a soft warm grey called Quail which is strong but not too dark, or a pinker grey called Yesterday's Flower. Farrow & Ball has loads of good greys - I think Cornforth White and Purbeck Stone are very easy to use, but you might also want to look at something with more green (Hardwick White is fab) or taupe (Drop Cloth).