Bought one of these bad boys in Dick's Sporting Goods a few weeks back.
Soft to the touch, yet firm in all the right places. Since hurting my lower back recently I've been using it in the car whenever I'm driving.
It doesn't look like much but man, it digs right into the painful spots in my back like the stiletto heel of an angry 5' 2" 104 lb. Thai masseuse named Mai Tai.
I highly recommend you get one. And a massage ball too.