We picked out a stationary entertainer this month...the Fisher Price Intellitainer. He will eventually be able to walk back and forth and turn all the way around in it. But for now his feet don't touch the floor! We happened to have a piece of wood that fit underneath in the footpath, so after covering it with a little rug, he could touch and bounce.
Despite the lack of any tummy time, Caleb's head control is fine, and has been since birth. I think the harness gave him extra stability that most babies don't have, therefore, never really had trouble with head control. And he is always trying to look around. He has always liked to lay tummy to tummy with you (which he could do with the harness on) and look around. So I called that 'tummy time.'