My personl site is hosted at hashbase.io (link) so that you can access it via dat and https. My canonical dat url is dat://pfrazee.hashbase.io.
Before I used hashbase I used Github Pages, and today it dawned on me that I can have dat://pfrazee.github.io work too. It's pretty simple if you know the dat dns spec.
All I had to do was add /.well-known/dat to my site (click to view). I put the raw dat URL of my site in that file, along with a TTL.
dat://40a7f6b6147ae695bcbcff432f684c7bb5291ea339c28c1755896cdeb80bd2f9/
TTL=3600
I'm still hosted at hashbase.io, but the dat site is "available" at the github.io domain now too!
Also note that it probably won't work for custom domains, since github doesn't (yet) support https for those.
Details: isaacs/github#156 (comment)