How to replace a piece of text in Emacs with a link or reference?

Question

When writing emails with Emacs, I like to use this format with numbers between square brackets to point to URLs.

Example:

The first version [1] is still buggy, so I have downloaded SomeAlternative [2] instead.

[1]: http://blahblahblahblah.com/version1

[2]: http://gaaaaaaaah.com/

Is there any Emacs mode or key sequence that allows me to quickly replace a URL with a reference in this format ?

Answer 1

There is the genuine footnote-mode minor mode.

Answer 2

org-mode footnote will do this.