I've been doing more and more Sharepoint these days, and I'm on a quest to find all the cool parts that I can find. One thing struct me right away was that you had to use Sharepoints framework, and override its methods, leaving your own custom controls lacking. Here's a use control that gimmicks up the framework to allow you to host your .ASCX controls.

Thanks to Mitch Ruebush for pointing out Jan Tielen's blog entry about SmartPart