In the early 90s, operating systems were getting pretty innovative and exciting. In a brief span of years we went from DOS and Windows 3.1 to having a myriad of operating systems that offered pre-emptive multitasking, memory protection, and different takes on how the user interface should be done.
Now, in 2005, we have Mac, Windows, and Linux which seem to become more similar each year. Most new features seem to come in the form of adding "content" -- bundling more programs with the OS as opposed to adding core features that only the OS vendor could realistically deliver.
The linked article below goes over five features that could be implemented into operating systems that could increase productivity, improve performance, and provide all kinds of new avenues for third party developers and users.