Very smart video game developers suggest how to make education more engaging and collaborative.
Z-type is free fun game that builds your typing and spelling skills. The adrenaline from playing the fast paced game triggers your brain to subconsciously learn the spelling of the words.
I stumbled upon an online game that is like SimCity. The way to get actions to occur to make improvements to your city is to have people click on links. So you send links to your friends or post them in your blog. Check it out and Increase Industry in the MyMiniCity of Merfopolis.
I assume the site makes money from advertising. They should get a lot of traffic very quickly. This follows one of the main rules of Evangelism Marketing, spreading the message benefits the user. Its both fun to see the city grow, plus you are helping your friends develop their cities. Pretty cool.