Tunnelblick:
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.

Viscosity:
Viscosity allows connections to be completely configured through an intuitive interface, without any need to know the command-line or OpenVPN's configuration file syntax.

Connect with the command-line interface:
A guide to using the OpenVPN's command line tool for connecting to Tunnelr.com services.

Using the network manager:
A guide to using Ubuntu's Network Manager for connecting to Tunnelr.com OpenVPN services.