Plus, if it's as much work to create a diagram as it is to do much of the programming (not to mention maintaining it), you're just not going to do it.

One type of diagram I have found to be truly useful, though, is the sequence diagram. I needed to integrate someone else's library into my application, and having this was a huge help.

If anyone has a pointer to a good sequence-diagram generator (that runs on Mac, preferably), I'd be happy to hear about it!