As part of my year-end planning I look at what charities to donate to, since charitable contributions are tax-deductible. Here's a list of charities with ties to free software, open source, and information technology.
Debian is my favorite Linux distribution. You can make donations to it through Software in the Public Interest -- make sure to explicitly set your donation to go to Debian. Debian uses donations to cover things like bandwidth and travel expenses for appearing at conferences.
You spend countless hours on Wikipedia. Where do you think the bandwidth and servers come from? Wikipedia doesn't display banner ads.