Indeed - 0% is a no brainer for a large purchase! Keep the money you were going to spend in the bank and earn (admittedly not much) interest whilst you repay the full amount.
I tend to agree, but sadly this also encourages "biting off more than you can chew". If you can't afford to drop the cash today, then what makes you think you can afford it tomorrow?
That being said, I've taken advantage of 0% XX-month financing from Apple, Newegg, and Amazon. So long as you pay it off it is great, but if you don't they can count all of the interest against you as if it was accrued the entire time.
I haven't gotten in trouble with that exactly. But I have run up a credit card that I received from an Apple 0% financing promotion on a vacation once. I don't regret the vacation but I should have prepared more ahead of time to fund it. Ate about $550 in interest last year on that dumb decision. So, they got me. As soon as I finish paying that off, I'm going to drop that card. I've already cut it up.