Custom Google Ad Sizes?

Do some larger sites get their own custom ad sizes in partnership with Google? Specifically, what ad size are they using on this site, below the article? It's larger than a 468x60, but smaller than a 728x90: http://entertainment.howstuffworks.com/question644.htm

 

using 300 * 250 will be good for ads..

 

Yeah, I know which ad sizes perform well. But that's not what I'm asking.