Left 4 Dead by Valve, is an online cooperative First Person Shooter which is best experienced by several friends all playing on the same server.
Although L4D ships with a dedicated windows server, the CPU requirements are high and hosting from a hired/bought dedicated server is the best solution. Many people have hired their own dedicated servers, but administering them is still quite a steep learning curve and the various console commands are not easily remembered, nor intuitive to use.
This application provides a web interface as a wrapper for various common console commands and administrative tasks.