Richard Thaler has a column in the NYT on making good citizenship fun. "Fun" can be used as a strong positive incentive to encourage a certain type of behavior, as in this viral video:
I liked this particular example:
Over in mainland China, lotteries are used for a different purpose: tax compliance. As in many parts of the world, China has a thriving cash economy, and it is common for small businesses like restaurants to evade paying sales tax. To combat this behavior, the government printed up special receipts that are supposed to be given to restaurant customers when they pay. Cleverly, each receipt includes a scratch-off lottery ticket, giving customers an incentive to ask for a receipt. Finance ministers in Southern Europe might take note.You may also want to check out this, this, and this video.