This is the time to bring out quiet activities meant for older kids like small lego, or mini cars - things he can play with without moving around a lot, are quiet when in use and that he can do without your help.

Nintendo DS would work well since he can curl up on the couch to play and is really resting - and there are plenty of math or learning type games too so you don't even need to feel guilty about it.

Listening to music with a CD player and headphones.

What he isnt' going to want to do is more of what he did all morning so it needs to be toys that only come out in the afternoon.