My assumption is that you are looking for a Windows equivalent to Webmin, however there are some potential other solutions too. Keep in mind a preference for strong authentication too! Enough with the caveats, here are some methods.
Remote display method over HTTP/S
client -HTTP/HTTPS- Server -remote display protocol- Server
You can install the RDP Active X control in order to do that.
Furthermore, you can use RDP competitors that have HTTP or HTTPS interfaces such as VNC and *VNC variants
Other options embeddable in webpages such as Citrix, and other protocols are options too.
You can use Windows 8 web based powershell, IPSweb, WebPSconsole, and numerous java applets, however, I don't think that is what you are looking for based on your comments.
Web based administration tools specific to hosting environments
This category opens up tools like Plesk, Webmin (limited Windows support), H-Sphere, Hosting Controller, and Cpanel (believe Windows support is in beta). Openpanel and others are heading towards windows support too. I think this category of tools best meets your stated requirements and is fertile ground for an analysis of alternatives.