It's a sad, sad day when they stop having naps.
My just turned 4 yr old stopped about 6 months ago. Then we had a bit of a blip when he started nursery school and was tired after school. We went to day nursery after school and they insisted he had a nap because he was tired.
We had a bloody nightmare at bedtime, where he wasn't settling until after 10 pm, making him more tired the next day. We had to break the cycle and told nursery not to put him down for a nap. He was tired at bed time and settled easily, he soon got back into his usual routine.
I used to love the golden 2 hrs between 1-3 pm which used to be nap time 