You may be aware of GeoGebra. In a previous post, our very own CP described it as “a surprisingly capable piece of free dynamic maths software, used widely by teachers and geometry aficionados”. I am preparing lecture notes for the new academic year and have been making diagrams in GeoGebra (on Ubuntu, since you asked), both to print in my notes and animate in my lectures. I can insert $\LaTeX$ labels and export as code for PGF or PSTricks. Here’s one:
Now, following a successful Kickstarter (which we covered in a previous post), GeoGebra have released tablet versions of the software. So GeoGebra is now available on Windows, OS X and various flavours of Linux (.deb, .rpm, other), as a Chrome App, a Chrome Web Application and in a ‘Java Webstart‘ version (though be aware that the Java Webstart is being phased out), and now for Windows 8 or RT, Android and iPad tablets. Here is a screenshot of the iPad app:
Download and more information at the GeoGebra website.