HotMath - This website will provide you homework help with specific problems that are in your textbook. It provides hints and tutoring to lead you toward the correct answer.
http://hotmath.com/

Math Forum - This site also provides math homework help. You can visit an archive of frequently asked math questions or ask Dr. Math questions of your own.
http://www.mathforum.org/pow/

Math World - Provides a dictionary of more than 300 mathematical terms.
http://mathworld.wolfram.com/