Here's another quick tip on how to see some more mail in your mailbox: check out Mail Me Some Art, a paper-based (postcards, ATCs, tags, etc) swap site.
Caveat: I've not tried it myself, I just saw a link to it on Twitter (thanks, @Taylormaidemom), but it sounds like a really cool idea that is guaranteed to have "no flakers" since you have to send something to receive something. All swap items are sent to the coordinator, who then distributes them.
From the Mail Me Some Art FAQs:
"All styles of art and all levels of experience are welcome. In order to guarantee everyone who makes something receives something in return, all swap items are sent to me and I mail them back out to others in the swap."There's no formal registration process, you just send items to the coordinator by the deadline. Has anyone tried this site or have experience with their swaps?
Oh, and by the way - enjoy the longest days of the year! Happy Summer Solstice (tomorrow), everyone!