I try to donate $50-$100 a month to open source software as I use it so much.
In the past I've donated to:
- Keepass
- Wikipedia
- Firefox
- GNOME
- Latexila (very nice LaTeX editor I've combined with R and knittR for dynamic reports)
However I'm sure there are a bunch of key projects that probably get ignored because they don't operate in the foreground.
What open source projects do you donate to?