In these countries you can be spied on, threatened or even jailed if you keep a blog that does not follow the official government line.
Belarus, Burma, China, Cuba, Iran, Libya, the Maldives, Nepal, North Korea, Saudi Arabia, Syria, Tunisia, Turkmenistan, Uzbekistan, Vietnam
This page has some information useful to bloggers in general and also contains a downloadable guide addressed to those living in countries where freedom of expression is probably not what it should be.

