OAST is a cross-platform front-end (GUI) for OpenVPN-client, allowing to manage multiple. It's quite simple in use and provides base functionality such as monitoring connection status. Application is written in Java so it works on both Windows and Linux
SSL-Explorer is a fully-featured, web-based SSL VPN server. This project is no longer actively maintained as the SSL-Explorer technology has now been acquired by Barracuda Networks, Inc.
OpenVPN ALS is a web-based SSL VPN server written in Java. It has a browser-based AJAX UI which allows easy access to intranet services. OpenVPN ALS is a direct descendant of Adito, which was a fork of SSL-Explorer.
VPNmonitor is a Java tool for network administrators to monitor VPN and SSL connections. The graphical representation makes it easy to visualize messages between computer nodes. Users can also read messages not of the above types in plain text.