Anyone have any good tips for making very straight hair wavy? I occasionally want to put some wave in my hair, and braiding it wet and letting it dry overnight never seems to do it for me (mostly because my hair is pretty thick and doesn't dry fully overnight when braided!)

Any tips or tricks?

You could try pin curls or rag curls.

Any type of curl and brushed out.  Brush, brush , brush and don't let the initial "results" scare you off from brushing more. ;D  Apply some setting lotion or other setting product to damp or actually dry hair and make sure your hair is completely dry again before brushing curls.