At five years old it may be a little young for him to be consistently interested in the same thing. I have a 6 year old and an 8 year old and about the only thing they are consistently interested in is playing with each other. I notice my kids will get into something for a few days and then they will move on.

I definitely understand your desire to wait to introduce computer games -- once you open that box, you can't close it very easily.

One thing that has really captured my 6 year old lately is listening to an audio book while he colors or draws. The combination of a story with something to do with his hands has been pretty awesome. Not sure how long it will last though.

Only other suggestion I have is to be pretty strict with a scheduled "quiet time" or "play time" when you make it clear that he has to entertain himself and you are not available to be a playmate. We do it for two hours every afternoon and it is a rhythm the kids have gotten quite used to, but I still have to defend it and keep the boundary clear.