To build great applications you don't want to guess on what to do, you can use personas to help you agree on common goals. If you know what you want to build you need great tools to help you build it.

One way to make it easier for assemblers  is to start thinking about plug-outs. What's that? Well if you're familiar with the concept of plug-ins you just have to think about it in reverse. Instead of thinking how others can plug-into your own software think about how your software could be reused by others.  Having the source code available is a great start but it's not the same as making it easy for your components to be reused. Common controls, common dialogs and widgets are examples of this type of reuse but it can be done at higher levels as well. By thinking about how your own code can easily be re-used you enable assemblers to build better applications.