That is the question we are dealing with these days.
Nathan has 8 teeth and I have a feeling a few more are on the way because the kid will not stop chewing anything and everything he can get his hands on! We're trying to teach him that some things are OK to chew, but other things are not OK.
So far we've addressed the following:
Gummy teething toy - OK to chew
Mommy's high heel shoe - Not OK
The string on your sweatshirt - Sure, why not
The corner of our entertainment center - You are a human, not a beaver
The buckle on your stroller - Doesn't seem too harmful
Books to the point that they are slowly disintegrating - We read books, we don't eat them.
Your fingers - If that's cool with you, that's cool with me
My fingers - Not cool with me
And of course, the old standbys are his tongue and his bath towel.