My Go modules vanity domain, as inspired by FiloSottile:
Apropos of nothing, with the Go module proxy there is no reason not to name your Go packages like http://filippo.io/age instead of http://github.com/FiloSottile/age. It just takes a couple HTML tags.
This way, you are not tied to a code host and can move without breaking your users.
To update, edit the MODULES list in generate.py then run it.