OEM OrigAudio Universal Portable Rock-It 2 Vibration Speaker 3.5mm - Black
I saw this product on TV and loved the idea.  Unfortunately, it doesn't stick well most of the time, and needs to be propped up which is not part of the design.  It doesn't sound good with most applications, you'll find yourself using a plastic cup most of the time.  Volume is very limited without distortion.  I found I would only use it to show friends how cool it was, then use a different speaker for actually listening to music.