Any software that has been around a very long time with entrenched data formats. These monopolies create a lot of problems at this point, and having the flexib

Any software that has been around a very long time with entrenched data formats. These monopolies create a lot of problems at this point, and having the flexibility to fork the code and create better tools (compatible with the data) would help. Some examples: Microsoft Word/PowerPoint/Excel, AutoCAD, Photoshop. It doesn't even have to be for the purpose of forking...I imagine Open Document for instance would benefit from just being able to see how the heck Microsoft interprets the data in its files.