When your first baby is born, you realize you would do anything for a few hours of sleep. Enter the Snoo. The price tag is hefty. But the parents I know who have one swear by it.  

The Snoo responds to the baby's initial whimpers as they come out of deep sleep into lighter sleep, and initiates soothing white noise and gentle rocking motions that are supposedly reminiscent of the womb. The baby is comforted back to sleep without fully waking. Gradually, the baby learns to "put herself back to sleep" unless, of course, she is very hungry, in which case she will wake and cry loudly for you.