Mischief is an app that I have been playing with lately; it's a very fast and
inexpensive drawingapplication that has an infinite canvas and is neither
vector or raster, but a hybrid. I have been using it for making annotations
on edits while working on UX and modeling concepts.
I've also started to use it on concepting; it's taking me some time to
appreciate its simplicity, mainly due to my reliance on Photoshop...
which is such a swiss army knife that you can get distracted or slowed
down by its features.
Arguably you can use other apps for a similar purpose, but on a Cintiq,
t’s very fluid for drawing; my hands seldom leave the screen/keys.
I have just started to experiment with using it for more robust drawing.
I came across this excellent video of illustrator Ryan Dening on Mischief
which makes it pretty clear that it's not a shortcut to talent, but a way
to keep from getting bogged down in deep software. Mischief is fairly
simple, clean, and elegant.