I'm not going to stay Open Source is the way to go, or that everybody must switch to open source (altough it would be very nice).
I'm working on a fully Open Source programms (UnCodeX), and while working on it I sometimes use other open source tools (FreePascal compiler) and components (RemObjects' PascalScript). Both the examples are open source (and free software, in a way).
PascalScript didn't compile for FreePascal out of the box, but because the source was available I could apply the changes required to make it compile. I mailed my changes to the developers and they applied them to their SubVersion repository. Now everybody can enjoy PascalScript in FreePascal.
As for FreePascal, the ini file classes provided by Borland in Delphi 6 didn't meet up to some of my requirements, and because of the
protected shit I could override some functions. FreePascal provided similar classes, and because the license of FreePascal is compatible with the license of UnCodeX (both are LGPL) I could use the FreePascal implementation and make my adjustments. While I was making some adjustments I discovered a few bugs in their implementation (the Delphi memory leak detection script by Vincent Mahon helped me to find one of them). I reported the bugs I found, and the fixes for it, and they have been applied to the standard distribution of FreePascal.
So, for at least two projects I found some issues, was able to fix them and contributed the fixes back to the creators. They helped me, I helped them in return. Sure, there are a lot of people that don't help out. But why shouldn't you? What would be the reason not to help others out that helped you at the first place. Please that report bugs are great, people that report bugs with correct patches are just awesome. And you can't create patches when you don't have source access.