The Electronic Frontier Foundation has posted an interactive map showing where the chokepoints are for online free speech, and which laws, proposed laws, and tactics can be used to force them to take your material offline:
Speech on the Internet requires a series of intermediaries to reach its audience. Each intermediary is vulnerable to some degree to pressure from those who want to silence the speaker. Even though the Internet is decentralized and distributed, "weak links" in this chain can operate as choke points to accomplish widespread censorship.
The Internet has delivered on its promise of low-cost, distributed, and potentially anonymous speech. Reporters file reports instantly, citizens tweet their insights from the ground, bloggers publish to millions for free, and revolutions are organized on social networks. But the same systems that make all of this possible are dangerously vulnerable to chokeholds that are just as cheap, efficient, and effective, and that are growing in popularity. To protect the vibrant ecosystem of the Internet, it's crucial to understand how weaknesses in the chain of intermediaries between you and your audience can threaten speech.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.