Guido Tschopp, a Swiss engineer, spent 14 years perfecting Sleepy, a set of four casters which, when placed under the corners of your kid's crib, helps "mimic the rhythmic movement of the uterus." Sleepy uses the baby's own movements and breathing to generate its gentle rocking motion. You don't believe me? Just ask the pirate earring- and soulpatch-sporting Swiss dad who stars in Sleepy - The Movie. Or read the happy parent responses in Sleepy - The PowerPoint Slide.
At roughly $300/set, Sleepy is twice as expensive as the Robopax BabySitter. But remember: the BabySitter rocks your kid along only one axis. Sleepy rocks your baby along three axes, x-, y-, and z. On a per-axis basis, at least, you're saving mad money.