Recently, I've stumbled on more self-hosting projects that help out different communities/groups/non-profits. Examples:

• RIPE Atlas Probe
• Tor Snowflake (or relay)
• Archive Team Warrior

With a hardware investment:

• ADS-B Feeder (need SDR)
• Weather Underground (need weather station)

What else is out there along these lines?

I'm less interested in things like CryptoCurrency nodes or mining (including things like Helium), or very resource-heavy things like Folding@home.