http://stackoverflow.com/
For all your CS programming related questions, c++, vb, javascript, java, c#, etc. Be careful what you ask though, their ban on questions is quite extensive, they really hate "dumb" questions.
http://math.stackexchange.com/ Similar: http://mathoverflow.net
Same as above but for math.
http://serverfault.com
""" But for servers..
http://superuser.com
""" for random tech questions
http://www.w3schools.com/
A website to teach you everything that you need to know to create a website from HTML to XML to PHP and AJAX. (To be honest, I'm only vaguely knowledgeable about these topics, I'm actually educating myself using this site haha)
http://codingbat.com/
For learning Java, and now offers Python education. Good for introduction and even "medium" level topics such as advanced recursion.
