This is cool, if you write your own http module by implementing IHttpModule you can subscribe to any events that it raises in the Global.asax, just like you would with Application_Start, Application_End, etc you can do the same with your own events with the signature ModuleName_EventName.

So if you had a IHttpModule, say, StatsModule with an event, Start, you can subscribe to the start event with StatsModule_Start.

Its described on this MSDN Docs page for ASP.NET Application Life Cycle Overview for IIS 5.0 and 6.0.

Very cool!