If you’re wary of browsing on wide open public Wi-Fi networks (and you should be), Sidestep is a free Mac application that routes your connection on an unsecure network through a secure proxy.
Sidestep automatically detects when you are on an unprotected wireless network and forms an encrypted tunnel to the proxy you specified during setup. Anytime you login a wide open Wi-Fi node (such as at a coffee shop, airport, or other public area) you won’t be broadcasting your login credentials and other personal information in what amounts to plain text into the air around you. Anyone snooping on you or the network in general will simply see your stream of encrypted data going to the proxy.
Hit up the link below to grab a copy and read additional information about setting up the program and finding/configuring a proxy server. Sidestep is freeware, Mac OS X only.