Some scientists use TeX or LatEX but for most people Word is the thing that writers use these days.
We could refresh the look and feel of the entire desktop.
I believe in true love. But I am easily satisfied.
So if we're going to build new applications that require a large time investment, like say movie editing - today that doesn't matter for the enterprise desktop, but eventually it will when we get closer to consumers - you really need to have a cross-platform story.
When it comes to .NET they've done a really outstanding job.
The software patent problem is not limited to Mono. Software patents affect everyone writing software today.