Writing code seems like my highest leverage activity. Where can I help? In light of the recent US election, I'd like to contribute. Ideally it'd be around secure communications, digital privacy, and helping activists spread their message and organize.
Welcome to the fray.
First: decide what your skills are, and where you can contribute.
Try the Tor Project first: https://www.torproject.org/getinvolved/volunteer.html.en
The community is great there and very accepting of newbies that have the skills.
Signal / open whisper systems also are open source and accept pull requests:
https://github.com/whispersystems/
Read the anonbib:
http://freehaven.net/anonbib/
Also, there are other mixnet/darknet projects that could use help, such as i2p:
https://geti2p.net/en/get-involved
And if you want decentralized, mesh communications, cjdns and the Hyperboria experiment:
https://hyperboria.net/
Don't forget: if you are a developer, you actually make money, too. Vote with your dollars as well - donate to these persons. Many are 501c3's and it is tax deductible for you.