I went through a crazy quilt phase years ago. For pillowcases, you'll need to make suitable washable substitutions - velour instead of velvet, poly instead of silk. Wash everything before piecing, then let your imagination take over! It's a great place to use bits of lace, doilies, ribbons, and such.
Will you be embellishing with hand embroidery, or using some of those shiny rayon threads?