Okay, so it doesn't behave exactly like a Real Lava Lamp. But it's free and it looks nice (a RLL doesn't slowly change colors either) so why not?

One similarity to a RLL: it'll bump up the processor cycles to keep your Mac nice and toasty warm. --Still, I like the rocket ship look and besides, with enough positive feedback the author might be inspired to model a RLL for real. (Although we can do without the thing leaking oil and gunk when it gets old!)