Annotate Pro

This is one of the greatest tools you can have as a animator. Annotate pro is a on screen drawing tool that lets you draw anything you want on top of your app , then when you hit right click you can go back and work in your app while displaying what you drew on top. therefore it is excellent for checking spacing , arcs , to mark the position of something you have to counter animate frame by frame , to give crits to people and to write funny notes on your coworkers monitors when they take a bathroom break. There is a 30 day trial you can try and the full thing costs 19$ or so anyway.

Click here to check it out.