yeah, Contiunously Variable Transmissions are great. You may want to check
this white paper out, from the great team of 217. Do keep in mind its patent pending. I believe they were one of the first teams to try out a CVT, and they were very succesful with it, it's great to be able to have full horsepower at any speed.
Also, CVT's are starting to be used in cars too. The 2005 Ford Freestyle is running with a CVT transmission, pretty cool.