The online community has picked "w00t" as Merriam-Webster's Word of the Year 2007. It is an interjection "expressing joy (it could be after a triumph, or for no reason at all); similar in use to the word 'yay.'"
Seriously? Last year's word, truthiness, captured the profound epistemological uncertainty of our time. A synonym for "yay" that you use "for no reason at all" just doesn't have the same cultural heft.