These days, everyone from the Dalai Lama to Bill Gates is on Twitter, the microblogging platform founded in 2006. During breaking news events like the death of Osama bin Laden or for following the Arab uprisings, it’s become an invaluable tool for keeping up to speed. But for many, it’s still just another place to promote their own work, rather than engaging in a more natural give-and-take. So how do you tell who’s really worth following? FP's got you covered. Here are 100 Twitter users from around the world who will make you smarter, infuriate you, and delight you — 140 characters at a time.