SleepingTime.org lets you stalk Tweeter addicts even more effectively
When people post many times every day, the very act of posting reveals some interesting patterns. For example, if you know what timezone someone is in and you follow them and see what times of day they aren't actively posting, you can figure out when they go to sleep and how long they sleep, on average, per night. Do you think that sounds creepy? That's what SleepingTime.org does, on a more massive and organized scale.
The author (Amit Agarwal of labnol fame) compiled several lists of notable Twitter users (Tech superstars, Bollywood celebs, etc.), but you can enter any Twitter username (DownloadSquad, for example).
ed note: Roll this together with Twitter's geolocation features and let the bedtime shenanigans begin!