One really snazzy idea that arose out of the difficulties I ran into in the last few days was the idea of a parallel blog rebuild -- a way to apply global changes to a blog, like a new theme, but in a non-destructive way.
Here's how it works. If you have an entirely new theme you want to apply, but don't want to disrupt your existing blog while the rebuild is taking place, you can have the entire rebuild performed in a directory parallel to the main one. Then when it's done, MeTal copies over any files that are not rebuilt by the system (e.g., media files), and renames the two directories. The old one can be retained for a certain amount of time and then deleted, or deleted manually at your leisure.
This mechanism might be something I can use in a general way for other things, so I'm going to mull it over and see where it goes.