Photoshop or a computer photo editing program
Step 1: Take a picture of your existing room or wall that you will be painting.
Step 2: Upload photo to a photo editing program like Photoshop.
Step 3: Select only the wall(s) in the photo and "color" them in using a color that you love. Do this again (as many times as you like) with different colors. You will then have several "samples" to compare. This will help you narrow down the right color that will give your room the wow factor you've been craving.
Here are some colors I've been considering: