OpenVPN is one of the VPN solution I tend to choose because it works on a
variety of system platforms and under some of the more extreme conditions,
including when I have to tunnel out via a HTTP proxy.
On a Mac I've been using tunnelblick for some time, but I found a new GUI
client which is far more polished on the GUI side: Viscosity.
Viscosity says it
provides a complete OpenVPN solution for Leopard (Mac OS 10.5) and does not
require any additional downloads or software.
Some things I like about Viscosity are the keychain integration, Growl
notifications and traffic statistics. (See some screenshots here.)
Viscosity isn't free of charge, but at USD 9.00 (somewhere about EUR
6.50) I find it is quite affordable. I recommend trying it, if you use