Oligopoly is a Monopoly-like game as a Java applet, directly playable from the Internet. It's written in Java and the object design is very true to the game. It should be easy to modify. It comes with nice graphics and is quite fun, although it lacks many features of the original game. It is currently only in German.
GTD-Manager is a software project planning tool. You can add all phases and activities for your project, including milestones, then see it all in a Gantt chart. What sets it apart from other planning programs is the milestone drift diagram. After creating several full plans, you can see by how many days each milestones drifted into the past. Diagrams can be exported to several formats using the VectorGraphics library. So far, only German versions of the software and Web site are available (English versions are in development).