Typogrify

Typogrify takes text, rich text, or HTML, and applies typographic best practices to make it look beautiful for display on the web.

It does things like smart "curly" printer's quotes, en-dash & em-dash, language-specific hyphenation, handles "widows", and a whole lot more.

It allows you to "client-proof" sites by applying all of these typographic nicities to text before it's displayed, no matter where the text comes from.

Typogrify also has some handy inflector functions to do things like give you the plural or singular version of a word, human-readable relative times/durations, human-readable file sizes, and more.