From A Discipline For Software Engineering, the main guide to the Personal Software Process, by Watts S. Humphrey:
Standard software parts can be developed and will be used,
... A suitably rich variety of available reusable parts can greatly improve development quality and productivity. You should thus thoroughly familiarize yourself with the standard parts that are available to you and consider using them in your designs. [emphasis added]
One of the most important links on my Mozilla toolbar is search.cpan.org's recent modules page, now improved and better than ever. I realized long ago I could never familiarize myself with everything on CPAN, but if I looked at new modules every day, I would begin to have a good grasp of what's out there. Sometimes when I write a program I go check CPAN to see if anything can help me, but more often than not, I draw on my knowledge of some interesting module I installed and toyed with a few weeks back.
Speaking of trying out new modules, I've recently learned XML::SAX, written my first not tiny LWP program, and started looking at SOAP. I'm sure a use for these will present itself some time in the next few weeks.