Cron string for Apex Scheduler

The information in the Apex Guide on the scheduling facility actually doesn't do justice to the cron capability available.  For instance you can schedule things to run hourly for given period of the day, but the Apex Guide doesn't provide enough working examples to illustrate uses like that. 

Here's a discussion on the practical use of the cron syntax, and you can tell quite a few people still doubt the advanced capability of the cron string.