Khan Academy supplies a free online collection of more than 3,400 micro lectures via video tutorials stored on YouTube teaching mathematics, history, healthcare and medicine, finance, physics, chemistry, biology, astronomy, economics, cosmology, organic chemistry, American civics, art history, macroeconomics, microeconomics, and computer science.
The APlus50 Online Tutoring Service provides the opportunity to schedule paid private tutoring
sessions at your convenience. Whether you need assistance with a college level essay,
a course, or need a little extra preparation for an exam, APlus50 can provide tutors
for a wide variety of subjects. Anything from nursing to business administration to
college level algebra is covered.
Wolfram|Alpha introduces a fundamentally new way to get knowledge and answers—
not by searching the web, but by doing dynamic computations based on a vast collection of built-in data, algorithms, and methods.
MathNerds provides free, discovery-based, mathematical guidance via an international, volunteer network of mathematicians.