After you are comfortable with LaTeX, you can explore these extensions to LaTeX.
Some are software that uses LaTeX and others are packages that you use within your LaTeX documents.
All of the following extensions are free.
|LaTeXiT||Mac||LaTeXiT is a really powerful equation editor for Macs. Allows you to type up equations in LaTeX and then saves the equation as an image file so you can drop it into other files (such as PowerPoint, Word, Keynote, etc.)|
|IguanaTex||PC||IguanaTex is an extremely useful equation editor for PCs. It creates an editable object to use in PowerPoint presentations. This means, you can go back and make changes to your equations|
|Code Cogs LaTeX Equation Editor||Online||You can type in your LaTeX equation and download an image file of it. Similar to LaTeXiT, but a bit more clunky|
TikZ is a powerful graphics system. It is based on PGF (portable graphics format), but you will be using TikZ to "talk to" PGF (the underlying system that tells the computer what to draw).
Using TikZ, you will be able to create simples shapes, circuit diagrams, 3D shapes, curves, plot functions, and much more.
TikZ has a very steep learning curve, so make sure that you are comfortable with LaTeX before you tackle TikZ. Once you get the basics down it is much easier to use than the regular picture environments in LaTeX.