I read over all the other advocacy howtos for Linux that I could find (I've listed them in the resource section at the end). They were almost all addressed to convincing end users (either business or personal) that Linux could meet their needs on a day-to-day basis. That's a very useful thing to do, but it wasn't what I was looking for. Only the Linux Advocacy Project came close to what I was looking for, and it didn't quite cover what I wanted. I wanted something that would help me approach organizations making software for other platforms and convince them to port their works to Linux. Since I couldn't find any howto concerning that I decided to write one.
In this howto I'll cover how to approach software companies and what arguments may be most effective in convincing them to port their programs to Linux. I won't talk about trying to convince them to release their Linux ports under open source licenses. While that might be a good idea, I think these things should be done in small steps. Advocating a port to another OS is much more likely to meet with interest than advocating what the company may perceive as "giving away" product, or advocating a radical change in their basic development model.