A pure payment system within an app. Say that someone builds a social network that lets you easily get in touch with people who have need of skills that you possess. They then introduce a token system - call it "karma", maybe - that you can grant to people who perform good deeds for you, and then if your karma is positive, you can grant it to others in exchange for favors or services. Since you only receive karma for actions you perform and it doesn't rise in value based on the efforts of the social network, it's not a security. It is a currency, however, and could fall afoul of laws governing currencies.

BTW, a number of games successfully have things like this, eg. Linden dollars in Second Life, gold in WoW, or tokens in FarmVille.