I remember using this in the past, and one of the advantages it had over Tor and I2P is that it automatically encrypts and reroutes all network traffic without requiring any application configuration. I believe it does this by creating a virtual network adapter and sending all traffic through the adapter.
What do you guys think about this? I think Tor/I2P could learn from the network adapter approach, as it gets rid of the whole problem of having to configure applications and wonder if any applications are still "leaking" completely.
http://www.iopus.com/ipig/