Which website (small or big, famous or unkown) has beed built in PHP did you like?
http://php.net/ (no-one ever mentions it in this sort of thread :()
i don’t see the point in this conversation. there are unlimited sites built in php … leave it at that.
What about Google?
Yahoo also is…
Flickr and Wikipedia are my favorites. Facebook is probably the most popular site built on PHP. Digg is also a fan favorite
That’s like asking which cars are made with [insert material here].
a few searches of your search engine of choice could give you this info 
what else? - just say any site you know even it’s yours.