JavaScript makes relative times compatible with caching - (37signals)
http://www.37signals.com/svn/posts/1557-javascript-makes-relative-times-compatible-with-caching

A pro-caching technique for presenting cachable relative times (e.g., "15 minutes ago")

I put together a new mini app for our new status site yesterday that needed exactly this technique. I wanted the content of the application to be entirely page cached, so it would withstand the onslaught if the terrible should happen and we need to redirect all trafic to the status site.