I just released Revolution4D, a free plug-in for the Realsoft3D modeler, which adds some OpenCASCADE features to that software.
Revolution4D allows Realsoft3D users to load/save IGES and STEP files, and also features some basic B-rep modeling tools, based on cascade.
A small project page is here:
Note that Revolution4D requires Realsoft3D to run, so it may be of little use to most forum users, but I am posting this topic here because it may be an interesting example of integration of OpenCASCADE in other projects.
In future, if I have some spare time, I'll improve this tool adding parametric modeling and other features.