Here’s a little known secret: you can add footnotes to a tumblr blog by switching your Account Preferences to use the Markdown[^1] editor. I looked at Marco’s blog[^2] and, after reviewing the markup, realized there had to be an automatic way to generate his footnote links. After extensive searching to no avail, I realized Markdown Extra[^3] has a few extra syntaxes (like footnotes). Nice!

[^1]: Markdown is my favorite syntax for plain text documents (and now blogging). I use it almost all day at [Crowd Favorite](http://crowdfavorite.com).
[^2]: [Marco](http://marco.org) is the co-founder of Tumblr and a very smart developer.
[^3]: [PHP Markdown Extra](http://michelf.com/projects/php-markdown/extra/) adds all the nicities you sometimes wish [Markdown](http://daringfireball.net/projects/markdown/) had.