BlackBox is a handy WordPress plugin that I’m going to have to try out for development. It adds a debug bar along the top of each page, with items that would be invaluable for plugin and theme developers but probably of little interest to bloggers who don’t like getting under the hood.
With the theme you can have a look at all of the globals, see any errors generated, and keep tabs on the MySQL queries (including their execution times) behind the page generation. It even includes a profiler.
