What a nifty idea! if you want creative envelopes, go to Maps, map the route from your letter to the other person's mailbox. Print them up, fold them into 8 by 11 envelopes (or smaller if you are sending cards). This would be cool for pen pals
A site that helps you combine your words and a picture. I can see this maybe with your favorite scriptures, favorite quotes, or maybe your favorite song. How about a wedding photo with the first dance song. Or wedding vows.