do you know what he's really afraid of? is it the dark, monsters, etc?
our son is also quite smart & we found that he simply started stalling at bedtime around that age because it was more fun being up with mom & dad than going to bed. :) by the same token, he was also legitimately afraid of monsters at the time. we started using "monster spray" & everyone has a different idea of what to use - air freshener, plain water in a spray bottle, etc. we used a lavender linen spray because lavender is a soothing, sleepy scent. worked like a charm.
we also had 2 nightlights, regular music (which has since been discontinued for quite some time) & white noise (a fan, a humidifier, etc.). we still have the 2 nightlights & white noise & chase is almost 4.5! it works though. we also found that a very consistent bedtime routine helped us tremendously - bath, brush teeth/take medicine, potty, 1-2 stories (depending on length) & 1-2 songs (depending on time).
we also promise to check on him when we go to bed, so he knows he's not abandoned in his room at bedtime. he still calls for us every once in awhile, but in the last year or so he's really mastered falling asleep on his own & sleeping in his bed all night.
sorry for the rambling, i hope it helped though!
J.
mom to chase (4.5) & paige (due 6.2.08)