When I type code like
IEquation equation = new SquareEquation();
and when IEquation and SquareEquation do not exist NetBeans show hints for creating class IEquation and SquareEquation.
NetBeans should also offer a Create Interface hint for IEquation identifier.
Max volunteered :)
I used this bug report as a demonstration of how to file enhancements for NetBeans IDE on my blog at http://netbeanside61.blogspot.com/2008/04/filing-enhancement-request-for-netbeans.html
I will update my blog post when there will be a resolution of this issue.