Yup!
Quite a few times actually.
My iPod from 4 or 5 years ago dies 2 days before its 3 year apple care was up, so they swapped it out. Awesome
My Mac Pro was riddled with problems. They replaced the mother board, the RAM risers, the ram and the graphics card at one point or another. This was the 2006 model. Total life saver. I think I definitely got the lemon of the bunch.
Those were my experiences. My MacBook Pros never had any issues and neither did my G5 Mac.
My husband's MacBook Pro had battery issues after 2 and a half years (it wouldn't hold a charge), so they replaced that.
My mom's white MacBook had hard drive issues. But that wasn't apple care actually, the drives were faulty so those were replaced by the manufacturer. I forget which one.
Either way, when I had Dell problems, they never made it this easy (I actually never got my Dell problems fixed. It's why I stopped using PCs actually. Had a Dell laptop and Desktop, both went to crap). It also wasn't easy to go into a store, hand it over and pick it up a day or two later as opposed to shipping a ****ing desktop somewhere and hoping it gets fixed.
I think AppleCare is worth every penny.