For a soft-spoken programmer from Buffalo, Nate Fanaro gets a lot of hate mail.

Every day, his Twitter queue fills up with messages telling him to die or delete his account. "I find you extremely annoying," one caller said in a voice mail. "You make little girls cry. What's your problem?" said another.

Fanaro is not a hacker. He doesn't take down Web sites or swipe credit card numbers. Rather, the 30-year-old prankster is the creator of the Twitter grammar bot @CapsCop, an automated account that finds people who tweet in all caps and, within seconds, fires a snarky correction back at them: "Give lowercase a chance," perhaps, or "On Twitter, no one can hear you scream."

The technology behind such bots is simple, which helps explain why so many tech-savvy grammarians have launched their own. Programmers need only write a script to search Twitter's data and respond to certain phrases, and they're well on their way to Twitter infamy. Some accounts reply to users directly, while others retweet the offending messages.