After spending a good part of the day being frustrated trying to get various plugins to work, it occurred to me that the plugin API needs a debug mode, something that dumps data to the page being served so one can see what the heck is going on when something goes wrong.
Why do I say this? Because most of the time a non-functioning plugin shows up as...nothing. No text. No fields. No anything.
That makes it awfully hard to figure out what went wrong.