This one is big.
patterns&practices released ASP.NET 2.0 Internet Security Reference Implementation including sample application and walkthrough document. The sample app is actually the ASP.NET reference implementation known as PetShop. That meams that the deal is "buy one and get another for free" – one for ASP.NET 2.0 implementation and the other is for Security.
The best part is that both are free and can be found here