Answer:
For creating moodboards or planning your room, you have OlioBoard and BHG's Arrange-a-Room virtual room planner.
For experimenting with colors, there's BHG's Color-a-Room tool.
Finallly, for finding art accents for your walls, there is Little Art Engine. It makes finding art easy by recommending art to match your style. You can then preview all the art you choose using a picture of your own room.