I like Open source software. My operating system is the one with the penguin, especially Ubuntu distribution.
All materials arise in Vim, then are typeset by LaTeX. My favourite graphic editor is Gimp, Graphs of functions are sketched in KmPlot, Geogebra and in Mathematica.
Fractals, like the above one, are generated by Fraqtive.
I do historical fencing, play the guitar. In summer I go hiking, on the weekends I do puzzlehunt: Sendvič, Bedna a Tmou.