Stack overflow uses IIS??
SO is also hardly something impressive from a UI point of view: it is a very simple UI really not doing much. Usenet readers from 20 years ago were way more capable than SO...
monster.com, break.com, ancestry.com, wildtangent.com, kbb.com, redbox.com , nordstrom.com , townhall.com, tunein.com, g4tv.com
Don't blame the framework, blame the developers.