Ok here's a gadget: YONANAS
The price fluxtuates on amazon.com; i bought it for $29 which seems a good price for it.
What it is: It takes frozen bananas (and other frozen fruit), and mashes it up into a consistency that is like ice cream.
There are video reviews of it all over youtube, lots of people (who are on a diet) swear by it. it's certainly a healthy alternative.
Personally I did not particularly love the taste of the frozen banana results (which is bizarre since i have been eating whole frozen bananas for years; maybe just a bad batch of bananas; a friend here really liked the banana results) but frozen peaches were great.
As to whether you really need a dedicated tool to do this.. You couldn't really use a blender as it would either fail to pulverize or make soup out of it from the heat. Another major advantage to a tool like this is that it is built to be very easy to clean. There are now alternative product competitors to this product that sell for similar price; they probably all function similarly.