ASP.NET Web User Control Library

I realize this is an old topic, but if anyone is looking for a solution for creating reusable user control libraries, it turns out it's fairly simple. Here are two good step-by-step guides along with source code:

From MSDN: Turning an .ascx User Control into a Redistributable Custom Control

From Code Project: Straight way to create ASP.NET user controls library

The second link provides a solution to the multiple dlls created by the first link.

Edit- (2) Seems to be a dead link. Here's the new link

https://www.codeproject.com/Articles/30247/Straight-way-to-create-ASP-NET-user-controls-libra

If you want to share controls among project, my experience has shown that the best way is to build custom asp.net server controls instead of usercontrols. User controls are good for sharing within the same project, but not over multiple ones.

For this purpose I suggest you to build a set of custom server controls inside a class library and use that on all of your projects.

This book does quite a good job at explaining the basics of creating server controls

Edit:
I'm currently developing a .net web server control library. I actually didn't follow any step-by-step guide. I mostly considered using the book I mentioned above and the MSDN library + Reflector, which is a great tool for inspecting existing MS server controls and learning from them.