If you use Cadabra or even just play with it, I would like to hear about it. Please send me an email so that I can get an idea of who is interested in this program. And remember:
The "rule of 3": It takes 1 unit of work to get something for yourself. It takes 3x1 units of work to make it so your office neighbor can use it. It takes 3x3x1 units of work so you can use it "in the department" and in courses. It takes 3x3x3x1 units of work to give it to the world for free without support. It takes 3x3x3x3x1 units of work to provide it to the world and support it.
So if you use Cadabra in your own work, please cite the papers "Introducing Cadabra: a symbolic computer algebra system for field-theory problems" and "A field-theory motivated approach to symbolic computer algebra" (see papers for publication details) to keep the bean counters happy.
Cadabra is available under the conditions of the GNU General Public License (version 3).