When playing with symmetry or the multitool, I wondered it would be nice if Krita had a feature like Sketchbook Designer had:
http://www.youtube.com/watch?v=W0hmSVhssUc

This is awesome for generating patterns or decorations, for example

Interesting gui... One part of it got implemented by a new contributor (Michael Martini) last week already: tilting the symmetry axis.