Tzumi Lava Speaker : Always wanted one of these lava lamps as a kid and the parents always said no. For the first day being plugged in, it really didn't do much. Then the lava blobs really began to take shape and I found myself sitting down for at least half an hour. The instructions say they don't recommend keeping the lamp turned on 24/7, which is the only downside because I'll have to turn it off and turning it on later means waiting about an hour for the formless mass at the bottom to start taking shapes again. There were no problems with the lava heating up. It did take a couple hours the first time to really get going. I suspect some reviewers didn't give it enough time.  My husband and I love the glow and ambiance it gives off.