RakNet is a networking API that is a wrapper for reliable UDP and higher level functionality on Windows, Linux, and Unix. It allows any application to communicate with other applications on the same computer, over a LAN, or over the internet. Although it could be used for any networked application, it was developed specifically for rapid development of online games and the addition of multiplayer to single player games.
Phaos is a browser-based MMORPG. It features character creation, the ability to purchase/sell/drop potions, weapons and armor, traveling, inter-player chat, the ability to fight in the arena, explorable dungeons, an admin system, the ability to trade with other players, and the ability to fight other players. A download is available for people running Windows who do not have access to or do not want to set up a Web server.
X-Plane is a flight simulator that reads in the geometric shape of any aircraft and then figures out how that aircraft will fly. It does this via an engineering process called "blade element theory", which involves breaking the aircraft down into many small elements and then finding the forces on each little element many times per second. These forces are then converted into accelerations, which are then integrated to velocities and positions. This gives X-Plane the most realistic flight model available for personal computers.
Quaqut is a simple program that queries Unreal Tournament 2004 (TM) game servers and retrieves information like those available while browsing servers in the game. That means information like server name, game type and current map, names and scores of players, and much more. It could also be extended to support other games.