Sending things in the post is pretty awesome. I have a fair number of friends who live far away and so sending things is good. Paying more for postage than you did for what you are sending? Significantly less so.
I have seen these teeny canvas panels in shops for a while, and had absolutely no notion as to how to use them. Till I decided to start sending things in the mail again. (see: 2012 resolutions)
I painted little pictures on them (stuck on some fish and a boat made out of calendar paper). Glued a little note card on the back. Sealed the whole thing with a coat of varnish-y stuff. And now there are tiny and highly mailable art cards to send to people!!
I really like them.