I posted this pretty embarrassing picture of my HTPC cable management (or lack thereof) to twitter a few days ago.
Since then I've made a 98% improvement by rigging a "cable basket" or "gutter" underneath my stand. I also removed some unused 500GB USB hard drives. I'll move towards a NAS or 2.5" USB drives in the future to minimize power cords/adapters.
There is still a bit more to do as far as hiding speaker wires behind my baseboards.
Has anyone else undertaken such a project? How do you keep your media center tidy?