This thing is a wonderful baby entertainer, made by the Baby Einstein company (also makers of the 'stein). It consists of a fabric star with a smiley face on it, and has a motion setting that activates flashing lights and plays happy baby music whenever it gets bumped. This is perfect for Hallie - lots of bright colors, and something that gets activated by her own excitement: she tends to kick her legs a lot, which bumps the soft support and rocks the Star enough to have it play some more.
She is usually content to hang out and watch the Star all by herself. There are also other colorful things hanging from the supports. The mat is also soft enough that she has taken a few naps on it.
Sometimes big brother Will joins her. Often this is at the request of mom or dad, and often it is to help her keep her sucker in her mouth if she starts getting restless.