I find myself doing this a lot with pencils, pens and sometimes keys, although I aim for 360 degree rotations. Don't know why exactly, but it does feel nice. Somedays, I just can't get the timing right and retire from the practice disgracefully with my hand covered in biro streaks.
My hand/eye co-ordination is quite good, so I can spend ages throwing a tennis ball against a wall and catching it. It is soothing to me and sends me into a minor-trance-like state, so yes, it works as a stim for me....