jQuery 1.8.3, HTML, CSS, JavaScript
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jQuery 1.7.2, HTML, CSS, JavaScript
derp
Very similar to FitText.js, but you can change the units of the font-size (pt/px/em) and the 'multiplier' is directly (instead of inversely) proportional to font-size.
fiddlin' around with mobile layout type stuff
less than 100 lines of javascript~