When I was running WordPress I wrote a small plugin to track stories, word count, status, etc. Part of the reason for switching back to MovableType is that it's running perl and I just love writing perl code.
Now that the move is complete, I've started on a Story Tracker plugin. Basically, it gives an author a nice little interface to keep track of a story -- title, word count, genre, if/when it's submitted/published. Basically a glorified spreadsheet. Coming from the Open Source world, I like doing things out in the open where other people can learn from my mistakes.
Once those basics are done and I'm generating some nice looking widgets for the sidebar to the right, I'm looking at adding licensing information (Creative Commons) and display options. It's all for fun, but hopefully in the end it'll be useful to someone other than myself.