Fun things you can do with internet identifiers like alex@gleasonator.com:

Webfinger (used by ActivityPub)

Nostr NIP-05

Bitcoin Lightning (dumb method)

Bitcoin Lightning (other dumb method)

Email???

These should probably all be part of Webfinger, since Webfinger was designed to do all of it.

Also it would be neat to build a little React app where you can enter an internet identifier, and it pulls all these URLs to give information about what it all supports.