I've been waiting for a solution like SSL-Explorer to come along.
SSL VPN is undoubtedly the VPN solution that many enterprises will be moving to. Yes, the cost for appliance based SSL VPN platforms has dropped dramatically with the SonicWALL SSL-VPN $200 coming in around $450 to $600. But if you want to roll you own, SSL-Explorer is the way to go. A single port-forward to a dedicated SSL-Explorer server and you're on your way.
From Nottigham, UK comes 3SP and SSL-Explorer, described as "the world's first open-source, browser-based SSL VPN solution. This unique remote access solution provides users and businesses alike with a means of securely accessing network resources from outside the network perimeter using only a standard web browser."
I've successfully deployed this solution in a development environment and found it easy to install, quick to configure, and popular with users.
May I suggest trying it for yourself here: SSL-Explorer.
SSL-Explorer can leverage Active Directory, and yet is licensed under the GNU General Public License and you can install it on Windows or Linux.
You can use the free version or opt for the supported, feature-rich SSL-Explore Xtra.
The feature list is long, just go check it out: SSL-Explorer.