ASP.Net PayPal Commerce Starter Kit

It ships as a .vsi download -- which means that if you have Visual Web Developer or VS 2005 installed you can just do "New Web Site", pick the Commerce Starter Kit, and immediately get a working commerce site w/ PayPal payment integration. The starter kit is a full-blown ASP.NET 2.0 app, and shows off using the new ASP.NET Master Pages, Login/Membership, Role Management, Profile, ObjectDataSource, and data access features. The end result is a very clean app that is really easy to customize and use. Best of all it is free. (s.gu)