Open VPN

Excerpt from the OpenVPN website:

OpenVPN is a full-featured SSL VPN which implements OSI layer 2 or 3 secure network extension using the industry standard SSL/TLS protocol, supports flexible client authentication methods based on certificates, smart cards, and/or username/password credentials, and allows user or group-specific access control policies using firewall rules applied to the VPN virtual interface. OpenVPN is not a web application proxy and does not operate through a web browser.

Open Simulator

Open Simulator

Use this program to host 3D virtual worlds.
Good for commerical or private use.
Works on Windows and UNIX.