Fluffies get excited about using fonts not on your machine
so they can be more artistic:

http://www.webmonkey.com/blog/The_Future_of_Web_Fonts_Looking_Brighter

But you can tell your browser to use specific fixed or
proportional fonts, overriding this crap. I suggest you
do so --you can set font sizes too, making it easier to
read at the resolution of your screen.