The Baby Einstein Lights and Melodies Caterpillar Bouncer was the bouncy seat we used with both my babies. The chair gently vibrates and helps to calm baby and put them to sleep. It has an arm that is detachable that has lights and plays 6 classical melodies (these are very soothing). Little toys hang from the overhanging arm, and older infants can reach out for those.
There are two modes to the lights. One mode plays the music when your baby jiggles the unit. The other mode is just 'on' or 'off' and when on this mode, the unit will light and play music for 15 minutes. The music also has two volumes, which is nice.
The seat is deep, and I found that my baby didn't slip even when I didn't latch the safety strap. It is easily removable for washing after the occasional, yet inevidible, diaper leak.
Sometimes with a baby that's a little bigger, the child is difficult to remove from the seat without first removing the bar overhead. But, this bar is relatively easy to remove. I have also been impressed with the battery life of this chair (which is good, since it is easy to leave the vibrating part on). This seat is a little pricier than other vibrating chairs, but I have found it to be worth it.