You can help Tor or I2P by joining as a relay. You can help peer to peer search YaCy, <a href="https://yacy.net" rel="nofollow">https://yacy.net</a>.
Things I did recently:<p>* Control the lights on the christmas tree<p>* Install Pi-Hole<p>* Run nginx and flask to serve videos of courses I've downloaded over the years.<p>Things I plan to do:<p>* Build an embedded operating system by following Stanford's CS140E course: <a href="https://news.ycombinator.com/item?id=25272229" rel="nofollow">https://news.ycombinator.com/item?id=25272229</a><p>* Control more LED lights
Depends what you're into. You can use the pinouts to control motors, or lights, or take inputs from sensors. You can use it as a tiny server. You can use the stuff on raspbian to learn programming. You can add a battery pack and have a tiny portable linux box. If you can dream it, you can probably do it.