With start of facebook five years ago ,  web 2.0 expanding  and start of social stuff we came to care & value public knowledge. But the back side of the coin is that we stopped to think at all. We stopped to analyze the data, we learnt about SEO & PPC marketing  and stopped to believe in it. Now we are going online to check out what other people think about smth , get their knowledge and share it with our friends.

I’ve got some kind of  list of public knowledge web services ( you can call it regular way - Q&A ) :

1. Aardvark ( vark.com ).

Aardvark posses itself as social search engine. It was found in 2007 by group of former Google & Yahoo employees. Went private beta in 2008 ( when i discovered them ). Backed with about 7m$ of Venture Capital with 30 employees it was acquired by Google in february 2010 by 50m $.

Aardvark gives you an easy way to register, find your friends on network. When you register you add your “tags” about things you know for sure - like “History of arts” , “PHP” , “Cloud computing” & etc. Afterwards add your e-mail/facebook account/IM ( google talk , yahoo messenger , AOL & etc ) for communication. Aardvark will send you the questions from others users on network , that’s tags are relevant to you . Who’s deciding that question is relevant to you ? No , there are no army of Chinese/Indian held desk workers. It’s AI ( artificial intelligence ) . AI is not one strong formula , it’s exanding & learning. I was receiving some strange question back to 2008 , when also number of actual users was so small. It is also AI who is helping to find right tag for your answers , and gives you number of people who can help you with this tag of question before submitting it.
It’s very funny, that guys left Google to make a start-up and now they are back in the Google. ( Actually there are 20+ such companies , one day i will make a blogpost about it )

Verdict : awesome product. Good luck guys !

2. Stackoverflow & stack exchange ( stackoverflow.com & stackexchange.com )

Launched in 2008 it became a network ( Stack Exchange ) of websites , one of most popular websites ever ( they have #259 Alexa rank - january 2011 stats ). Backed by VC ( seed was lead by Union Square Ventures ) , don’t have bunch of annoying banners & annoying context advertising. ( It seems to me, that they are making revenue out of adding small icons of Microsoft product to related questions ) .

StackOverFlow team describe it’s website(s) as community knowledge exchange for programmers & IT-people. They also call it great mix of Wiki + Blogs + Forums + Reddit/Digg. Now Stack have lots of “communities” starting from old ones , stackoverflow - general programming questions , serverfault - server management  & configurations , api\apps and to some new stuff like “Cooking”, “Tex & LaTex” , “Photography” & “Atheism” ( full list here - http://stackexchange.com/sites ). Officialy StackOverFlow uses ASP.NET 3.5 MVC , that caused lots of open-source ( php, python & etc ) copies - like askdev.ru , OSQA , shapado.

Verdict - Very huge database of Q&A , unfortunately , half of it is real garbage.

3. Reddit Own Community.

Yeah , exactly. Great stuff. Don’t tell me anyone isn’t using it. Google is using it for App Enginge ( “Platform as a Service” cloud computing solution by Google , launched april 2006 ) forum , help for developers. Reddit was launched in 2005 ( 9 months after digg.com ) , and was acquired by Conde Nast ( additionally owns Wired & Ars Technika ) after 14 months.
This solution came as experiment. Adding publish of open source, that caused great impact & bandswitch growth experimnt ended with “happy end”. According statcounter.com Reddit became more popular than Digg.com

Verdict : Great for some uses

4. Quora ( quora.com )

Quora posses itself as online knowledge market. Found by former Facebook CTO Adam D’Angelo in 2009 went online in 2010 , backed with 11m $ from Benchmark Capital it is becoming very popular Q&A website. And this is why :

• Lots of Quora-related topics on very popular blogs as Techcrunch , Venturebeat & etc
• Due to Adam , who brought lots of “Tech Starts” to help answer the questions - Dustin Moskovitz of Facebook , Fred Wilson - Union Square Ventures & etc.
• All questions can get updated by other users ( post-edited )
• Lots of companies ( like foursquare & linode ) are checking out questions about their services and answering ( It’s not me to say you, that’s really awesome feedback , great solution for creating hard brand valuation )
• Quora gives awesome tools for organizing UGC ( user-generated content ) by users themself

Verdict : Really awesome service, unfortunately i can’t find good ways to use it for me

There are lots of other services like Mahalo , ChaCha . I find Quora is better than first one , and ChaCha is a bad mix of Aardvark & Quora.

Also i want to mention Hunch ( hunch.com )

I love hunch, i enjoy every second using it. It’s better than Q&A , it’s better than any marketplace, it’s better than any recommendation service. Most of question are ” Should i switch to Mac ? ” , ” What external drive should i buy ? ” , ” What 3rd party twitter application should i use ? ” or ” What country should i take vacation to ? “.
Hunch uses it A.I. algorithms to measure & analyze peoples choice , using data you provide - your tastes , income , place of living , age & etc.

Verdict - I first met such thing as e-commerce about 10 or more years ago , now it’s best thing i have ever seen