Woot is a term used to show extreme exuberation in joyous agreement. It is best expressed by teen girls excited by an upcoming situation or just to display common happiness.
-"We need to get some new summer fashions"
-"WOOT"
or
-"We are cool"
-"wOOt"
Exclamation of technology obsessed people (h4x0rZ, gamers, even txtmsg freaks) indicating feelings of excitement and satisfaction. I believe it originates from "What now, bitch!" which was shortened to "What!" and then 1337-ized to "w00t".