Online WYSIWYG Editor to write and share mathematics:
- Quickly insert mathematic symbols with Suggestion Box
- Tools to draw graphs or diagrams, and export to SVG
- Import/Export Latex for Math Mode
- Share documents with people
PhET provides fun, free, interactive, research-based science and mathematics simulations. The simulations are written in HTML5 and can be run online or downloaded to your computer. All simulations are open source. (from the product's site)