The Interop Forms Toolkit 2.0 is a free add-in that simplifies the process of displaying .NET forms and controls in a Visual Basic 6 application. Instead of upgrading the entire code base, these applications can now be extended one form at a time. The goal is a phased upgrade, with production releases at the end of each iteration containing both Visual Basic 6 and Visual Basic .NET forms running in the same Visual Basic 6 process.
Most importantly, the Toolkit guides you down a migration path that allows you to focus on writing code that adds business value instead of infrastructure and interop code.
Interop UserControls allow you to host any .NET control on a Visual Basic 6 form as if it was a real ActiveX control. This means you can extend your existing Visual Basic 6 applications by taking advantage of the rich library of controls that .NET has to offer.