I have been struggling lately with Davey to try to get him to nap. He will stay in his bed (amazingly) but falls asleep usually only every 3rd or 4th day. I would leave him for at least an hour, but usually by that time he was yelling loud enough that I worried it would wake Charlie, and that was not worth the break from him.
Then I consulted my "sleep bible" (aka Healthy Sleep Habits, Happy Child - which I would recommend to anyone) and it had two recommendations for a child who is trying to drop his nap prior to his 3rd birthday:
1) Make a poster (all bling'ed out and fun to look at) with these sleep rules:
At bedtime we...
- Stay in bed.
- Close our eyes.
- Stay very quiet.
- Go to sleep.
2) Reward following the sleep rules with a treat.
Yes, the book actually recommends a food reward and cautions that "this method is guaranteed to fail if the treats are insufficiently motivational." I found this method surprising, but I like it! The author explains that social rewards (smiling, hugs, praise) just aren't powerful enough to change a strong-willed two-year-old (describing Davey right there) who is fighting sleep for the pleasure of your company. It's easy and I knew it would work with Davey if anything did.
So far it has worked very well for us (and I actually didn't even make the poster - I planned to, but the treat for falling asleep was working so well that I haven't needed to bother with it yet). Now Davey gets a cookie every afternoon if he falls asleep. He slept 5 days in a row after I began rewarding him.

The second day, he asked for a glass of milk with his cookie (just like Daddy).

He kept repeating, "I dip it, I eat it. I dip it, I eat it...."
Yahoo for cookies & milk!