Thanks, doesn't really need to be cordless. I'm more interested in using it to rotate my tires. I'll take a look at that though. Is there anything I need to look for in particular? What kind of power or will any of them be good enough to do that?
It depends on what you mean by "good" and what your attitude is toward price and quality. Rotating tires isn't a really frequent, heavy duty application. You might find something that's far from top-of-the-line but handles your needs quite sufficiently.
If top-of-the-line isn't essential to you, then you could take a look at Harbor Freight. www.harborfreight.com They are showing 1/2" electric impact wrenches in the $30-70 range.
I've had one of their air powered impact wrenches for years. It works fine for the occasional tire rotation or rusted-on nut. (Removing the lug nuts, not tightening them! That's a job for a torque wrench.) But I probably wouldn't have bought from Harbor Freight if I were running a tire shop or a pit stop and needed a tool that could stand up to that sort of load.