Global Voices has an interactive map showing bloggers who have been threatened, arrested, or killed for speaking out online. The United States has one — Elliot Madison was taken by the FBI for spreading word on Twitter on how to evade police arrest during the G20 protests in Pittsburgh on September 24th and released on bail shortly after. China has the most with 33 on record; Egypt is a close second with 29.
Threatened Voices via Erin Biba on Twitter