Spirit

Caused quite a stir when it first launched as everyone was still buzzing around Snapchat

@jtzou shared this a while back on MessageMe. Neat concept. Could be useful for marketers / companies to use for promotions or expiring deals.

Total bummer: it doesn't work anymore. The dev told me so on Twitter (due to API changes). But now I can't find his tweet, so maybe he's got something secret working again, haha.