It's hard to commit to anything, none the less, living with lime green walls, or red walls that you thought would be a deep burgandy. HouseBeautiful has an online paint color tool that lets you experiment before you dip the brush.

How it works: Pick a room type from a drop-down menu Pick the area of the room you want to paint
Click on paint swatch and experiment with selections of paint from Benjamin Moore, Sherwin Williams etc..
Print out your choices and pick up the paint at your local store..
No Mess!