If you're procrastinating on Twitter anyway, might as well train your mind while you're at it. Here are two simple games that make use of the microsharing service's functionalities and keep your brains busy while tweeting:
Follow @TwitBrain and get served calculations on a regular basis (like 3 per hour). If you're the first person to reply with the correct answer, you'll earn one point and hopefully make your way to Internet fame (well, not really) by getting on the top 10 lists.
Follow @BeatMyTweet and do the exact same thing, but this time with word scrambles. Warning: it's ridiculously easy so be fast if you want to be one of the first 10 to reply with the correct answer. Leaderboards here.