Peek-a-booty (a.k.a Peekabooty) is a project started by the famous hacker group CULT OF THE DEAD COW but now run by its own open source group that is entirely separate from the cDc. Its aim is to provide a way for everyone - even people whose internet access is blocked or restricted by their State, e.g. China - to surf all of the web using a peer-to-peer anonymous proxying/caching network.

How it works
Peek-a-booty works by forwarding your web browsing request to other Peek-a-booty nodes, that may either forward your request further or actually fetch the requested page.
Imagine you are node A, and you live in a place where your internet access is blocked. Using Peek-a-booty, you will forward your request to node B, and you will have your requested page in return. What you don't (and can't) know is how your page was fetched: it's quite likely that node B forwarded your request to node C, that forwarded it again to node D, that actually requested it. After the page was obtained, it goes back from node D to node C to node B that finally sends it to you.
As the network will be built mostly of dial-up accesses that will keep changing their IP every time they dial up, and that nodes keep popping up and then vanishing, you realize it would be quite a mess to filter out unwanted IPs for the censors.

Peek-a-booty transmit all data in an encrypted form using a 128-bit SSL HTTPS protocol. This was chosen because it is not only quite secure, but it is the one used by e-commerce and web banking systems worldwide: filtering out Peek-a-booty nodes by protocol would destroy the secure commercial Internet nearly completely.

A demo version of Peek-a-booty was shown at CodeCon in San Francisco on February 17, 2002. It was originally due for the late 2001, but it's not finished yet, though its release should be quite near. It will be released under the GPL licence.

Pros and Cons
The big pro of the Peek-a-booty model is that you can surf the web in full anonymity and bypassing any filter. The cons are that it will likely use a lot of bandwith for residential users and that when your node will be actually fetching files your IP (and not the originator's) will be logged. So I would not like to have my IP logged while unknowingly fetching illegal pornography for somebody else's enjoyment.

Reference sites
The official Peek-a-booty site is (no, not that offers a different approach to.... hmmm... deep browsing).

If you have more resources to add, please msg me).