• monopd — server for monopoly-like games
• Capitalism
  • .deb installer?
  • for Ubuntu, just build it, it's not that bad. First: apt-get install qt4-qmake libqt4-dev
• Kapitalist
• gtkAtlantik
  • it's in the Ubuntu repository, but I ran into an unrecoverable crash-bug with it
• lots of good info at psmonopoly.com