Prove my website identity / domain verification. It would be great if I could show my verified website URL on my keybase profile.
The summary for keybase would be:
1) on your website, add a link to your keybase.io profile with a rel=me attribute. (e.g. <a href="https://keybase.io/aaronpk" rel="me">keybase</a>
2) on keybase.io, click "verify my domain" or "prove my website identity", and enter your domain
3) keybase will crawl your website and look for the rel=me link to your keybase profile, and the verification is complete
App.net announced "domain verification" using this process last year, you can read about it here: http://blog.app.net/2013/04/29/announcing-domain-verification/
For the crypto part of the verification, you can have people create a URL containing everything like the Github gist.