There are several great drills in the cordless screwdriver category. To get right to the point Makita's 7.2V offering has tons of torque, 177 pounds actually. That's more power than some 18v offerings. And it comes in a nice package and is comfortable to use. If it didn't have one serious drawback we wouldn't even consider recommending another drill. But the Makita's offering doesn't have variable speeds. And if you're going to be driving a lot of screws that may be a show stopper. After lots of searching we found Dremel's offering. It excels at letting you control speed. It's also compact which is great for getting into tight spots.
The Dremel 1130-01 7.2-Volt Screwdriver/Stylus Combo excels at being a screwdriver because it allows you to control speed and is very compact, allowing access to tight spots. We've listed it here as a combo with the Dremel Stylus because with the combo price you might as well get both.
The Makita TD020DSEW 7.2-Volt Cordless Screwdriver is impressive, especially if you're looking for torque: