Last time I bought a (refurbished) computer, I did research on https://wiki.debian.org/Instal.... Worked out of the box.

Wrong. I work in a French bank, and our contract management system is written in a French programming language: The variables are in French, the comments are French, the function names are in French, the operators are French... For example, "if" is "si". It's unbelievable for outsiders, but this is real.

I suggest leather instead. A proven concept, and won't make your back hurt that much.

Just a couple of thoughts:

• Join a mailing list and help people out if they have got problems that you can solve. You cannot image how easy to answer some question are. But they take time to answer. Write an FAQ.
• Help the developers getting information. For GNumeric, that would be for example providing EXCEL sheets that don't work with current versions of GNumeric. For GPhoto, contact any manufacturer that won't release specs for their digital cameras and ask for information.
• Translate projects.
• ...

It's not all about money...