Should you ever run out of caustic things to say, you ll find ample inspiration at http://www.passiveaggressivenotes.com. An evil twin of postsecret.com, the site houses painfully polite and hilariously hostile writing from shared spaces the world over. Also check out their blogroll for similar sites.

To have your personalized notes illustrated – usually featuring a caricatured man, a robot and robodog – send an email to Sam Brown at http://www.explodingdog.com/. Or watch many of the already illustrated musings of other senders.