Smoothie maker is very much like a blender, The key differences are of course it has the spout and it usually only has a couple of speeds that are optomized to make smoothies. The key difference is they also have a "Stir Stick". The knob you see on the top of the smoothie maker is actually the handle to a large plastic stick that extends inside of the hopper. While you machine is chopping up the ingredients you can use the stir stick to make sure all of the frozen ingredients get pushed to the bottom of the hopper. They work incredibly well and we use our all the time. By the way I saw on on sale to day at Walmart for about $28. I think it was a Back to Basics brand but it looked almost identical to my Sunbeam.
By the way I am still waiting for a home ICEE machine as well. I know they sell the one at Toys R US but it is just not the same. Unfortunately I do not know if you could use one at home to make it worthwhile. But hey, if practicality mattered to any of us, would we be here in the first place?