w00t is Merriam-Webster's Word of the Year for 2007

Voters at Merriam-Webster's Word of the Year 2007 poll have chosen "w00t" as 2007's most iconic word. M-W says that the word is a gamer's acronym for "we own the other team," but I'm inclined to think that that's a backronym, a back-formed acronym created to explain a word already in use.
1. w00t (interjection)
expressing joy (it could be after a triumph, or for no reason at all); similar in use to the word "yay"

w00t! I won the contest!
Submitted by: Kat from Massachusetts on Nov. 30, 2005 23:18

Link (via Ars Technica)