For a very long time, the web was filled with very plain fonts.
Unpleased with this lack of variety, a group of developers invented sIFR, which used Javascript and Flash to replace boring text with lively fonts. But sIFR had a problem: not everyone liked or used Flash. It was also slow.
Then, David Chester created typeface.js. typeface.js was brilliant in that it was purely Javascript, with no Flash involved. But typeface.js was slow to load and required large files.
And most recently from Simo Kinnunen came cufón, More info can be found here.
