I'm not sure but I think I'd like a "angle list" similar to what some illustration apps like ACDSee (previously Deneba) Canvas and others provide.

I typically have my rotation snap angle set to 15 degrees but some apps allow you to specify arbitrary angles; "15,30,45,60,90..." etc.

This lets you specify exact angles instead of a single angle step.

However, having that isn't too important - either way as long as the angle is a user config'd option...

-Will