Cache-bust pages containing embedded content
The saying goes, there are two hard problems in computer science: caching, naming things, and off-by-1 errors. While Drupal certainly has not solved the naming things, it has made a valiant attempt at a decent caching strategy. And for the most part it works great, allowing millions of lines of code to load up quickly the vast majority of the time.
This is more a tip about our favorite automation tool, the Events, Conditions, and Actions (ECA) module, and how it can get you out of a bind when Drupal caching goes too far.