Pick a sport, any sport. Sure its fun, but its more fun to win (usually).
http://kidshealth.org/teen/food_fitness/sports/sports_pressure.html

Clients and employees are always jockeying for position. will x person leave your company to go work for google? Will x company outsource to India or elsewhere to save money?
http://www.monster.com

Of course :)
http://www.makefive.com

Business takes the game player into the real-world, where the stakes are measurable. I think this works on two levels: it makes work fun, and it makes games seem like a pale imitation. (Frankly, I don't think that we'd be working such long hours if it didn't seem so exciting.)

Like it or not, if you love someone its possible at some point there will be someone else their eye could wander to. It happens, can be very tough depending on which side of the coin your on.
http://www.love.com

Japan seems to always lead with so many innovative technological advances. Its always a race to find the next best thing.
http://www.nytimes.com/pages/technology/