Thought I would mention something I found which appears to be maintained unlike sslexplorer, adito, openals. Hypersocket VPN | Free software downloads at SourceForge.net
I used this recently to give access to our network to a contractor. He was a mac user, it has a mac client. Don't expect a browser based solution, but i was able to define some hosts/ports that they could access (in this case our Active Directory since he was developing an app that needed to access it). When they connected, he had full access to any host and port I defined. It appears to use some combination of tunnelling and socket redirection.
So just publish your RDP resources, when user connects they just access the RDP server like they are on the same network. I guess the launching feature of sslexplorer made us lazy but i sent email to developers to ask for launching feature.
Maybe this is one to watch, something to take over from the well loved, but neglected sslexplorer project.
