Web Forms MVP is a simple Model-View-Presenter framework for ASP.NET Web Forms.
There are more specific packages for interfacing it with your IoC container of choice.
It helps you build testable and maintainable ASP.NET Web Forms-based projects.
It features support for normal server controls, data-binding and async pages.
It is additive, so you can adopt it one page at time.
Since 2009, Web Forms MVP has served hundreds of millions of web requests across numerous production sites.
It has been downloaded over 15,000 times. (Some of those were before we went to NuGet, so you need to check a few places if you want to add that up yourself.)