Parents: What are some good birthday gift ideas for your pre-schooler's friends?

My daughter is 3½ and has been in pre-school for all of three weeks now, and has just gotten her second birthday party invite. I am wondering what other parents think is a good gift to give or to receive for this age group.

I know kids get and have so much stuff (toys, etc.).

I know kids like to receive presents.

Do you set a “cap” amount for spending? Do you have one all around good gift you give all kids, which they all seem to like? Do you go shopping for each gift/child individually? Or do you just give gift cards (which I am not opposed to, but I know for myself, I have a pile of them and I find them hard to keep track of and therefore, spend).

The last birthday party my daughter was invited to was for a boy turning 4, and in my desperation, I asked a shopper in Walmart, who had children. She suggested Spiderman pajamas, and then I got two other Spiderman items, so it was like a “theme gift.” However, since my daughter is now invited to these two other kids’ parties, I don’t know the kids and I need some guidelines on future shopping so it does not make me crazy.