what are the other websites you prefer to ask or answer any question?

i have bookmarked the following forums to ask or answer any question. what are the other websites that are as significant as these according to you?

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Programming - Nairaland
www.quora.com
Consumer reviews on Movies, Cars, Bikes, Mobile Phones, Music, Books, Airlines, Restaurants, Hotels & more - MouthShut.com
in.answers.yahoo.com

thanks in advance