Oh my gosh, I'm a little slow on the uptake here, but I just saw that the great PostMuse is featured right now on the Postcrossing blog!
PostMuse is not only one of my favorite pen pals, but also one of the greatest mail enthusiasts around -- she sends a ton of mail and it's all thoughtful and awesome. Take a look at the excellent Postcrossing blog post about her, where you can learn about her history with Postcrossing plus see some wonderful photos of her amazing home mailbox, and the mailbox where she sends mail, and her P.O. box. (Yep, it's like mailbox porn for mailbox geeks like us.)
She wrote a fun post about it on her blog, too - I love it when all these fine internet resources to revitalize mail all cross digital paths!