This question was born from the discussion in comments under this answer.
Чё is a slang/colloquial word, but does it mean что or чего? I believe that it's the equivalent of что, although it can't be substituted in all cases - and I used this in my answer to the linked question. However another user stated that I was wrong and that the correct meaning is чего.
So, which meaning is correct?
UPDATE: It was suggested to me that it can mean both, e.g.
Чё тебе надо?
Что тебе надо?
Чего тебе надо?
However in this case, I'd say that in the last example (чего тебе надо), чего is in itself a colloquial form of что, hence it can't be argued to be the meaning of чё.