Randal Schwartz used to have a great column in the now defunct Web Techniques magazine. Each month he would focus on a specific topic. There were many times that I found myself reading through his code and learning something totally unintended (that is, not the topic of that month's column) - an odd 'map' or 'grep' statement, an unfamiliar syntax using code references or hash slices, etc. I would frequenty be forced to go look things up just to understand what he was doing.

My point is that you can learn a great deal by reading other people's code (especially if they're really good programmers!). All of those old Web Techniques columns are still available at www.stonehenge.com/merlyn/WebTechniques

You can also find tons of interesting code on CPAN - just search for one of your favorite modules that you use all the time, then click on "view source" and prepare to be amazed!