Coogle
Coggle is a freeware mind-mapping web application. Collaboratively create notes and diagrams. Login with your Google Apps account.
Lucid Charts
Lucidchart is a web-based diagramming software which allows users to collaborate and work together in real time to create flowcharts, organisational charts, designs, mind maps, and many other diagram types. Login with your Google account.
Google Sheets
How to make a graph or chart in Google Sheets
Desmos
Graph functions, plot tables of data, evaluate equations, explore transformations, and much more – for free!