In Cow Clicker, you click on cows. Which gets you points that you can use to buy more potential clicks to use clicking your cows. That's about it - but that's the entire point.
I'll readily admit I don't know much about Facebook games myself - the most exposure I get to them is catching a glimpse of FrontierVille on Susan Arendt's screen every once in a while - but either way, they're big news. Casual gamers and Facebook users love them, while hardcore "lifestyle" gamers think they're the spawn of the devil.
Love them or hate them, they're making splashes all over the place - and one designer has made a Facebook game both designed to poke fun at Facebook games as well as act as a case study on those who play them. Cow Clickers, a game by Ian Bogost, is a game where you click on your own cartoon cow, and that's it.
In six hours, you earn another click - and every click lets you buy more clicks. You can buy additional clicks via microtransactions called "mooney," you can publish notifications that you have clicked your cow, and you can click your friends' cows as well. It is a Facebook title boiled down to its purest essence.
According to Bogost's blog, Cow Clicker is "partly a satire, and partly a playable theory of today's social games, and partly an earnest example of that genre." It's also slightly brilliant. I mean, those cartoon cows are pretty cute, and you just know that a few of the people who start playing this game ironically may find themselves addicted to clicking their cows before too long.
You might surmise from the existence of Cow Clicker that Bogost hates Facebook games. As he discusses in the (excellent) post, he does - but not because he doesn't think they're games, and not because they're games played over social networks, but rather because of "the way in which these games were games." If that sounds confusing to you, it's probably meant to - I heartily recommend reading the full deal.
But if you don't have the attention span to read the full thing, why not go click on your cow? They're awfully cute ...