Psiphon
http://psiphon.civisec.org

What it does : Allows users to access blocked sites in countries where the Internet is censored with out installing additional software. Psiphon turns a regular home computer into a personal, encrypted server capable of retrieving and displaying web pages anywhere. You can then give out access to friends and contacts who live in a censored Internet environment.

What it wont do : It won't allow you to access secure or encrypted web pages (HTTPS) and it won't protect you from malicious websites.

Suggested Use : Give key people and stakeholders uncensored access if they are inside countries that are censoring the internet.

Who Owns It : CiviSec Project run by the Citizen Lab at the Munk Centre for International Studies at the University of Toronto. http://webapp.mcis.utoronto.ca/

Tor
http://www.torproject.org

What it does : Tor protects you by encrypting your communications and bouncing them around a distributed network of relays run by volunteers all around works with many of your existing applications, including web browsers, instant messaging clients, remote login, and other applications based on the Internet's TCP protocol.

What it wont do : It won't keep you anonymous if you visit websites that use Javascript or Flash (these plug-ins should be disabled). A lot of care must be taken even if you have Tor installed.

Suggested Use : For activists who want to use the internet in countries that surveil and censor internet use.

Who Owns It : An non-profit organization called the Tor Project.

Resources
Ethan Zuckerman's Guide to Anonymous Blogging with Wordpress and Tor