We did food gifts for ours. I made chocolate covered pretzels. They were a hit, and I think would be relevant for most ages. For the youngest ones, you could do those apple sauce pouches or something.
For $1 a piece at AC Moore (craft store), I found little stuffed animals on a key chain that are also a change purse. I wasnt sure how they would go over but I see the kids have them hanging on their backpacks at school.
DS' birthday was a few weeks ago. I got the birthday Play-Doh, divided up a bag of (generic) Play Doh tools from the One Spot at Target, and those little coloring book Play Packs also from the One Spot. I usually put in fruit snacks, but I had plain M&Ms left from Halloween, so I threw those in instead.
Re: party bags