Ask HN: How to maximize utility with my tech skills while I'm unemployed?

I'm without work and am looking for another programming job but it's not something that really comes easily for me. To keep fresh on my tech skills I work on side projects.

I also know I have to work on my interviewing skills, and have been to multiple interviews. But in the meantime, I still want to be useful to others with applying my tech skills. I feel like they're going to waste as long as I don't have work. Open source contributions are one way I know of, but are there any others?

My experience in programming is mostly in web development (>7 years, PHP mostly with lots of JavaScript/HTML/CSS) with hobbyist C++, C#, etc.