R.S.
Hi S.,
My daughter was also not a good napper until about 9 mos. or so. That was when she started taking 2 naps and we could really get on a schedule. I have a few suggestions:
1) Try going for a walk w/ the stroller, wearing your son in a front carrier around the house (we would use the Ergo carrier with the sleeping hood up to get my daughter to sleep), putting him in a baby swing, or going for a drive. My daughter was more likely to take longer naps doing any of these things than in her bassinet or crib.
2) Elizabeth Pantley, in her book The No-Cry Sleep Solution suggests that you wait outside the door starting 10-15 min. before your baby is likely to wake up. The second you hear him stirring, you should go in and soothe him back to sleep (using whatever means necessary -- pacifier, rocking, etc.). This is supposed to encourage him to take longer naps. It didn't really work for my daughter, but it might be worth a try.
3) You son might be old enough that you could try letting him cry himself to sleep for one of his naps. Check on him every 5-15 min. and pat him (but don't pick him up). This might be hard to manage, but might actually work.
Getting walks/fresh air even when it's not nap time can help. So you might want to take a walk be for naps. And having some sort of pre-nap routine (can be similar to, but should be different from bedtime routine) such as reading a story, nursing or having a bottle, etc., might also be helpful. Having a regular schedule (can be somewhat flexible) might also help your son know when he's supposed to be sleeping, eating, etc. This can be hard to do, but it really helps.
Whatever happens now, it WILL get better as your son continues to grow and develop. Until then, best of luck!
R.