I've seen a lot of great projects on Two Peas in a Bucket where transparencies are used. They make cool windows in scrapbook pages and awesome looking cards.
Finally, I got myself a pack of transparencies and gave it a shot. Tada! My first project! I'm already addicted! I love the way this card turned out! I owe much of my success to Two Peas in a Bucket for their Finally Friday video series by Kristina Werner. A couple weeks ago she made a cute transparency card that gave me the basics and tricks to working with see through materials, after all, you don't want your adhesives showing on the backside!
If you would like to see Kristina's video yourself, log onto http://www.twopeasinabucket.com/userblogpost.asp?id=39817 and get ready to learn something fun and new!