What are good resources to self-teach mathematics? I am teaching myself mathematics using textbooks and I'm currently studying the UK a-level syllabus (I think in the USA this is equivalent to pre-college algebra & calculus). Two resources I have found invaluable for this are this website (http://math.stackexchange.com) and Wolfram Alpha (http://wolframalpha.com). I am very grateful that with those tools, I have managed to understand any questions/doubts I have had so far.
Can anyone recommended other valuable resources for the self-taught student of mathematics at this basic level?
I hope questions of this format are valid here?
Thanks!

This is an old question, but this is for anyone else who might want this in the future.
For direct information about the a-level search TLmaths on YouTube, who has a playlist of just under 1000 videos covering the entire course.
For lots of free practice questions visit physics and maths tutor. 
I have recently found openstax for many great maths books, but is not specific to the a-level.
Professor Leonard on YouTube is great for any level of maths, and has great lectures.
I hope people find something here to help them learn.
