I used to look at FOSS as a means to get free software: MySQL, Apache, Eclipse etc... FOSS is part of my day to day affairs and I dare say the best thing to ever happen to software and software developers.
But for me, FOSS is the best programming howto guide there is. It is like a living text book that is always getting better. I have learned more from reading other peoples source code than I have from any book, blog post or article. Being an autodidact, reading source code makes much sense than reading the English words used to describe the programming concepts.
Just this week I was asked to R&D a bunch of stuff and I found solutions for all the CF stuff by going to either CFLib.org or RIAForge.org. (Mad props to Ray Camden for making those sites. You saved my ass twice this week dude! Rock On with your bad ass self!)
Those sites are gold mines for CF programming knowledge. I have been turned on to so many new ideas and concepts by the folks that have shared their work that I want to give a shout out and thank you to y'all.