Drupal hit it big when version 5 came out. Before this time it had a considerable user base, but it hadn’t gone main stream yet. The transition from Drupal 4 to Drupal 5 was extremely quick. No one held on to Drupal 4 and all significant modules released 5x versions within a few months. When Drupal 6 came out last year I think many of us expected the same kind of quick upgrading and transitioning, but alas, and many important modules have taken their sweet time coming out with a 6x release.
If you’re in the web development or software development industry then this list will probably remind you of situations you’ve encountered. If you aren’t in the business then I hope this list is educational.
Won’t do #1: I won’t build a site for companies that I consider to be unethical.