The New Gamer's R. LeFeuvre overlaid a series of Gradius playthroughs to provide an idea of the average paths players used in proceeding through the level.
If you're familiar with Gradius, you'll find some of the variations interesting. And it gets you thinking about how other games would average out with a similar averaging map.
At this point I'm especially curious how top down pathing visualizations through frequently run 3d maps (like WoW raids or instance dungeons) would turn out. I'm guessing you'd see some very well established cowpaths between the key encounter areas and techniques for each area. But then, optimal approaches to maps and encounters are the currency you trade in when playing MMOs.