For those who may not be familiar, gamification refers to rewarding people with fun, scoring, ranking, or achievments for interacting in ordinary ways which motivate them to exhibit behavior you wish to encourage.
Done correctly it is a fun and meaningful means of motivation.
Done incorrectly it tends toward leaving users feeling manipulated or obstructed from their task.
If you've ever used any of Stack Exchange's websites, they feature this sort of concept heavily and have ranking paths for different types of activity/users like asking questions (will rank up your Student ranking), answering questions (will rank up your Teacher/Professor status), improving answers by adding an illustrative image, video, etc., or voting other answers as useful/correct or not.
Here's an index of Stack Exchange's sites: http://stackexchange.com/sites
Non-website examples can be seen in the videos at VW's old marketing site from a few years ago: http://www.thefuntheory.com/