>well, yes and no ;)
>
>I went back and read the two pieces of documentation that I have on them. What I'm a bit hazy on is the benefit that custom interfaces provide. I'm sure they do, but I'm just not quite 'getting it'. After a year and a half, I still find myself in 'learning mode' with .NET!

In addition to what Bonnie said there's also the compiler enforcement of the interface, which is very important. So if you create a new control, the compiler will tell you what methods and properties you need to implement. For databinding you generally just cut and paste the logic, which unfortunately is the only way since there's no multiple inheritance.

In Windows Forms you could look into Extender properties which would allow you to add properties nad methods to existing control and only write the code once. But this is relatively slow and inefficient and definitely not a good choice for something as commonly referenced as databinding controls.