Environment Emitters

These objects are invisible in Live Mode but allow you to add environment effects and emotional auras to a room without having to place specific decor. The objects are reasonably priced (based on how many of the The Sims 3 reward lights you would need to place) so you can use them in a normal game without feeling like cheating.

You will need to enable debug objects (using the bb.showhiddenobjects cheat) for these to be available. They're categorized under Lights > Misc, but it's much easier to just do a search for "environment emitter".