Comment by kgo

Keybase lets you do some key stuff, but the bigger feature is that it provides a bunch of ways to authenticate the source of a key above and beyond the WoT and getting into the strong set. Authentication is an inherently hard problem. With keybase you can, for example, see that the key that you want to use to send an encrypted email to [email protected]'s website is owned by someone who also controls [email protected]'s twitter, reddit, github accounts, web-site, etc, making it less likely that there's a MiTM going on.