Keybase is more than a website. If you're comfortable working in a terminal, you should download the keybase app. You can do so much with it: sign, verify, encrypt, generate messages, sign code, move keys around, etc., all using GPG for the crypto.
Our recently-announced project is live for select testers.
Every account on Keybase has a public history. "Sigchains" let Keybase clients reconstruct the present without trusting Keybase's servers. And when you "follow" someone on Keybase, you sign a snapshot of your view of the claims in their sigchain.
Documents describing Keybase's use of cryptography.
Design, implementation and specification of our upcoming teams feature.