On Becoming Pre-Toddlerwise has some great tips on snacks.
Snacks are something I think are often very different from home
to home, even among homes where parenting styles are similar.
This is just fine; a snack is used when you need it, and the
need for it varies from home to home. Remember to start as you
mean to go on. Before you start "snack time," be sure you think
through what you want snack time to be. Pre-toddlerwise says
"The best snacks will be low in sugar and salt" (page 59). I
agree with that. Healthy snacks are the way to go. "A snack is a
snack" (page 60). A snack is not lunch nor is it dinner. It is
not a meal. This means it is not large. You don't want the snack
so large that the child will not eat the next meal. If your
child isn't eating well for the meal following a snack, this
does not mean that your child does not need a snack. It simply
means your child needs a smaller snack. This is really where
"snack time" differs from household to household. For some,
snacks happen in the morning be