Sherwin-Williams color visualizer. For the longest time, I wanted a cobalt blue kitchen. I finally got it, so now I have moved on to obsessing over a yellow and teal dining room. Whether or not I will eventually have an actual dining room remains to be seen, but it can't hurt to plan.
(And lest you think I'm smoking crack with my color choices, know that after I put the yellow on the walls, the color visualizer actually suggested teal for the accent color. Disregard the red on the walls in the background. Also, I would never put that style of furniture in a room this color. Think unfinished pine and Moroccan colored glass lanterns. Not that I'm a fan of pine in general... but I digress.)