Wall colours really are a personal thing, there's so many elements you need to consider:
What's the natural light like? North facing rooms are usually colder as they get less light, so warmer colours can help make the room feel more cosy. South facing rooms are usually (depending on the windows) flooded with light so bright colours can be dazzling.
Certain colours are linked with certain emotions/reactions e.g. reds and yellows are frequently used in restaurants as they are considered warm, relaxing and can increase appetite (so could be used in a dining room unless you're on a strict diet). Calming colours like blues and greens are good for bedrooms.
Then you've got the size of the room (linked with the natural light) darker hues can make a small space look smaller.
As pinkowl says, it also depends on the other objects you're going to be putting in the room. coordinating furniture, the floor material, lighting, soft furnishings, ornaments and pictures all plays a part in creating a unified space.
I've always been a fan of light flooring and white walls (for any room) as it acts as a blank canvas. You then create the atmosphere in the room with all of the other things mentioned above. This is especially true if you have a lot of pictures on the walls, because coloured walls can affect the look of the images.
However, when we get into our new house we're going to be using some very subtle soft accent colours in most of the rooms to add a bit of personality. It's a Victorian terrace so for a few of the rooms we'll be installing a dado rail and painting the lower half of the wall in a soft colour with the upper half white to hang pictures.
