I must say that I sleep much better at night since I started doing automated testing on web apps. You still miss stuff, but usually it's pretty obscure. That's one thing about XP programming that I totally agree on.

On the usability front, I try to make it as easy as possible for users to comment on the application as they use it... some sort of feedback link to a form that records as much information as I can get (browser, url, action, time, etc). This gives me a nice database table todo list without having to sift through and reply to dozens of emails.

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