Instructables has a nice tutorial on how to create motorized skates using a pair of inline skates, an angle grinder, and a bag of 12 volt batteries. And just how safe are these? Well instead of brakes, this is how you stop:
In this version, I just put trust in my sense of balance and lifted my foot off the ground while flailing to find a power cable to rip out.
Although I'm too much man to use roller skates. No, instead I just strap live bears to my feet and have them carry me around.