Good for Mozilla, putting their money where their mouth is and setting an example. It would be great if they or someone with sufficient reputation setup a way to make it easy for others to contribute financially to FOSS projects, a central payment clearinghouse.

In my for-profit organization, we thought we should contribute to the free / open source projects that we were using and which were helping us make money. We wanted to pay our share.

We started by putting together a list, and that's pretty much where it ended. The list was enormous. Try it yourself, and don't forget the components of other products that are FOSS. EDIT: Here's Mozilla's attempt at making such a list, which they label "incomplete":

https://wiki.mozilla.org/MOSS/Projects_in_use_by_Mozilla

On one hand, it reflects the incredible contribution of FOSS software. On the other there was no way, in a busy workplace, we were going to spend days tracking down all those FOSS developers, finding ways to send them money, and implementing it.