For people who would like things to be a little more "mathy" around here, I found a wonderful post on Sarah Rainsberger's blog, WhenItRains, with all sorts of online Math resources for secondary Mathematics.
With Sarah's kind permission, here they are!
"Many of these are lesser-known sites that I stumbled upon and didn’t want to forget, so you won’t see a lot of the *famous* math sites here. Consider this to be mostly a list of hidden treasures."
Sites with Free Video Math Instruction
Khan Academy: http://www.khanacademy.org/
Patrick – Just Math Tutorials: http://patrickjmt.com/
Purple Math: http://www.purplemath.com/modules/index.htm
Cool Math: http://www.coolmath.com (also has sections for younger kids)
The Math Page: http://www.themathpage.com/alg/algebra.htm
SOS Math: http://www.sosmath.com/algebra/algebra.html
Algebra Help: http://www.algebrahelp.com/
Virtual Math Lab College Algebra: http://www.wtamu.edu/academic/anns/mps/math/mathlab/col_algebra/
HippoCampus Algebra: http://www.hippocampus.org/Algebra
Online pre-calc (alg/trig/geo) random test generator: http://esaab.math.missouri.edu/mucgi-bin/munew.cgi?variable=trig
EdHelper Algebra: http://www.edhelper.com/algebra.htm
Stat Primer: http://www.sjsu.edu/faculty/gerstman/StatPrimer/
Stat Trek: http://stattrek.com/
HippoCampus Statistics: http://www.hippocampus.org/Statistics
Sites That Are Mostly Calculus (many include algebra reviews, too)
University of Houston Math Help Online: http://online.math.uh.edu/
also includes most senior high school/intro university topics including study and practice exams for AP Calc
Aid for Calculus: http://www.jtaylor1142001.net/calcjat/Contents/CalcCont.html
Paul’s Online Math Notes: http://tutorial.math.lamar.edu/
Find the Error: http://www.dougshaw.com/findtheerror/ (Finding errors in solved problems)
HippoCampus Calculus: http://www.hippocampus.org/Calculus
Cool Online Tools
Online Fraction Calculator: http://www.helpwithfractions.com/fraction-calculator.html
Prime Factorization Calculator: http://www.mathwarehouse.com/arithmetic/numbers/prime-number/prime-factorization-calculator.php
Equation Calculator: http://www.algebrahelp.com/calculators/equation/
Most Common Errors in Undergraduate Mathematics: http://www.math.vanderbilt.edu/~schectex/commerrs/
Interactive Mathematics Miscellany and Puzzles: http://www.cut-the-knot.org/index.shtml
Online biology textbook with summaries and practice questions: http://www.mhhe.com/biosci/genbio/maderbio6e/
Thanks so much for sharing, Sarah!
By the way, Sarah Rainsberger is a self-made expert on University admissions for homeschoolers in Canada. Her website is full of excellent information for homeschoolers who are looking at what is required of them in order to attend a Canadian University.