Is it possible to connect to a remote OSX machine using OSX, Linux or Windows in a way similar to Windows' remote desktop?
One simple way is to turn on vnc screen sharing by going to System Preferences -> Sharing -> Screen Sharing on the machine you want to share. For client compatibility reasons you may need to select both "Anyone may request permission to control this screen" and the "VNC viewers may control this screen with a password" checkboxes.
Once you've set up the machine for sharing you can connect to the screen on OSX using the Finder sidebar [SHARED] section or on linux using one of the many vnc clients (vinagre, vnclient etc.).
X11.app also works well for client/server UI separation if you want the app to run on the Mac side with local access to the filesystem and peripherals, but draw the UI on the remote machine over the network.