OpenVPN GUI for Mac OS X
http://code.google.com/p/tunnelblick/

Android的OpenVPN-Settings
http://code.google.com/p/android-openvpn-settings/

OpenVPN GUI for Windows
http://openvpn.se/

如何在 Debian / Ubuntu 服务器上架设 L2TP / IPSec VPN
http://apple4.us/2010/05/setting-up-l2tp-vpn-on-debian-ubuntu.html