Shaman conveys the pictures that most humans cannot see; many people did a good job as a Math Shaman.
An online graphing calculator and more than that! You don't need an account to access it, but an account can keep what you have drawn. Try the examples below:
Previously known as SageMathCloud, it is the most easy way to experience the power of SageMath, an open-source mathematics software. See here for Sage Basics [ipynb sagews] and A Tour of Sage. More tutorials are available in my ModularSage repository on GitHub. You may download the following worksheets through the icon inside the link. If you upload the worksheet to your own account, then you may execute the codes.
"TikZ ist kein Zeichenprogramm!" TikZ is package associated with TeX so that you can program and generate graphs. Check out my New Year Cards (cards before 2014 not by TikZ) and my TikZ Studio for examples. The source codes can be found here.
(You may change filename.pdf to filename_solution.pdf for the solutions.)