A demo version of Unrealty, the oddball real estate demonstration program that's based on the Unreal engine has been released, and is available for download. You'll need a retail Unreal CD to run it, but here's what's contained in the 12 meg download (which does in fact feature network support):

The demo features the full demonstration level of the headquarters of the Heartland Business Park, a real business park on Long Island, NY, including an interactive, talking tour guide who leads you on a seven point, repeating tour.