Well, we can't write any plugins that you can actually activate from within the game; we'd need the source code and only Aaron has that
So unfortunately anything you want to get into or out of the actual game data would be typed by the player...
I'm hoping Aaron puts in the ability to write plugins into SE5, since some of us around here ARE avid programmers who would love to create a space empire game ourselves but just don't have the time or motivation to do the whole thing...