$5

The no-bullshit approach.

"When Sidestep detects you connecting to an unprotected wireless network, it automatically encrypts all of your Internet traffic and reroutes it through a secure connection to a server of your choosing, which acts as your Internet proxy. And it does all this in the background so that you don’t even notice it."

"Tunnelblick is a free, open source Graphic User Interface (GUI) for OpenVPN on Mac OS X. It provides easy control of OpenVPN client and/or server connections."