Video games, breathing, inappropriate thinking, cigarettes (I really need to quit that), eating, using the bathroom, porno, and saying stupid/inappropriate things. I'm also falling prey to an addiction to the forums here, but I like to think I have that under control.
And much like Furburt, I recreationally enjoy a non-opiate substance. I could never get a taste for Vicodin... tends to make me sick. I can't say I'm addicted to caffeine because I can't tell if it still has an effect after all these years. I can't remember ever having a sugar buzz, but if you take a handful of caffeine pills at once, within about an hour you start to see some really weird things and talking at a hundred miles an hour. Then you throw up for a few days.
I avoided the temptations of WoW since it began, I've never even tried a free trial of that junk. Seems like a nasty thing to recover from. Surprised no one said they are addicted to their Ipod or Iphone yet.