Perfect thread for me :-) I'll also give examples as some are difficult to explain.

GAW 5+/10+ ETC. - generate a word which has 5+ or 10+ letters. same applies to GMW 5+/10+ instead you create many words with that amount of letters.
STB - stop the bus. a letter is given, for example: B. then 3 topics, such as girls name, country, boys name. you need to list things which fit into the topics that also begin with B (e.g bella, benin, ben) all of them must begin with the same letter that was stated.
N3 - name three. host will give a topic, like colours, and you name 3 colours. quite simple really
GTS - guess the singer.. speaks for itself i think.
XS - name song. so, you're given a singer, like adele, and you must name one of their songs, such as hello.
GMN - generate many names. same concept as GMW except with names rather than words.
STAB - the host says STAB_________, and the first username typed under that line is out. it can be outloud or silent.
ANTI-STAB - rather than the first username being out, if the game is trivia races, they move forward, or if p2k they choose who to kick.

Can't think of anymore ATM but I'll be sure to edit my comment when I do :-)