iRAPP Server for Mac OS X
Has display mode management and multimonitor support.
Most important for you are the options -
[ ] Allow multiple users to connect simultaneously
Act on remote users access:
[ ] Switch user to hidden session
[x] Switch user to console session
It is a licensed implementation of the Microsoft RDP protocol for the Mac OS X operating system. There is also an enhanced remote client for the iRAPP server. But I just use the Windows Remote Desktop client because its usually on whatever PC. Its also nice to have an RDP client for the Mac to use. I found plain VNC too limiting. The Teamviewer flavor of VNC is better in a wan scenario but doesn't forward the audio in either direction like iRAPP.
Microsoft's "Remote Desktop Connection Manager" is like PuTTY for SSH in that it saves connection preferences and displays interactive active thumbnails when concurrently logged into lots of servers, Windows running rdp, Linux running xrdp or OS X running iRAPP.
It has a lot of interesting features like a Unity mode for launching apps remotely and unifying their output with the local desktop (vdi for the Mac). Or just viewing the desktop. It also brings the audio output from the Mac to the local system. The iRAPP server appears as another sound output to the operating system.
I use it to watch television on a Mac Mini running EyeTV3, which is recording shows from a HomeRunHD network tuner.
Its a little pricey at 80 dollars but since its practically running Microsofts version of SSH on the Mac for remote management it is a lot more satisfying.
I was apprehensive about buying into it at first, but after about a year it really feels like a good purchase. Even strange Windows to Mac keyboard stroke mappings work.
There isn't a lot of documentation on using it for Home Theater or AppleTV/Xbox extender mode.. but in general that's what it enables you to do. You have to turn off the powersaver mode on a mini and make sure the iRAPP service starts up before logon. But I just let it run, the mac rarely reboots.
They currently haven't an automap of server drive letter to remote drive letter (over the RDP tunnel) C:\server\ to F:\local\ or vice versa. I believe that is in the works. But while RDP supports it, implementing it between two dissimilar operating systems is not a trivial thing to do, certain preconceptions have to be made and assumed.