Slate has a neat article on Peeps' relationship to Easter. Here's a quote:
This Easter Americans will consume an estimated 700 million Marshmallow Peeps. Some will also be consumed by them—fanatics maintain Web sites featuring everything from Peep erotica, dubbed "Peep Smut," to an inventive online movie called "Lord of the Peeps," and each year at least a few newspapers print odes to the candy. But for all the fascination with Peeps, it's never been clear why the sugary treats are associated with Easter. The marshmallow rabbits represent the Easter Bunny, but what do marshmallow chicks have to do with the resurrection of Christ?