Bondo. It may be a brand of body filler, but it's also a word the uneducated throw around to imply a repair is amateur. In fact, it's just the opposite. Watching those hot rod shows on TV you'd think that everybody was using lead to smooth a body panel and that lead is the only professional way to repair a car's body. One of the top restorers of vintage Porsches in the country once told me if the factory had body filler in the '50s, they would have stopped using lead the day they discovered it. It's a superior product, and much easier to use. Besides, lead is toxic, especially when heated. There are more than a few old body repair guys out there with nervous system problems.
So why does body filler have such a bad rap? Like most good things, take them in excess you have a mess. Body filler is great for filling small blemishes, shallow body damage or repair seams. the problems arise when filler is laid on in 2-inch thick patches. The repair almost never lasts, often resulting in the filler falling off the car on a cold day. If you correctly apply body filler, you'll have a well done, smooth repair.
Check out this easy tutorial on properly applying body filler and you'll be repairing your car with finesse.