GPSBabel has grown beyond my wildest imagination when I released this free software in June of 2002. It is downloaded and installed nearly 700 copies per day.
Most of the development and support is done by a small group of volunteers. There is a constant stream of requests for help, additions of new hardware, improved support for existing operating systems, and so on. We have a ready stream of expenses for web site hosting, tools, GPSes, mapping programs, and seemingly endless requests of time.
How can you help us?
If you're a programmer or a web creator, we have obvious things for you to do. We're always in need of more help.
If you're a writer, we can always use a hand with the doc. If you're good helping people diagnose problems in email, helping to answer questions on the mailing lists helps free up developer time.
If you're handy with geospatial software specifically or just have a gift for teasing good questions out of people so we can help find answers, those are superpowers we always need.
Finally, we also try to 'pass the plate' to defray costs. Less than .01% of our users have historically done so. We accept Paypal (you need not have a Paypal account!) and are looking at other ways of defraying the cost.