I have a few UFO piles... some of them move from pile to pile - some have been stuck for years. There is the - started, and got far enough to see what it looked like pile - the blocks together, waiting for borders pile/combined with a finished top waiting for quilting pile - and then there is the quilted waiting for binding pile.
The funnest part for me is the challenge of something new - so I start something and loose interest quickly once I see I can do it and get a pretty good idea of what it will look like. I think that's why I like the bargellos and OBW so much - you're never really quite sure what it will look like until it's done.