Instead of feeling bad, pitch in money when you can, but even better pick one you could contribute to and contact the maintainers asking how you can help. Then you're giving back and improving the software along the way, I don't think you'll feel bad when you're contributing time to an open source project. The tech world runs on open source, use it and give back when you can.
Re: Ask HN: Am I the only one who feels bad for using free software?
#11I'm at the moment looking forward to it. I'm just having some trouble learning other people's code and navigating it, but i guess that's a skill you have to develop by doing it.