First off, screen captor is GREAT. I have spent a long time looking for a screen shot manipulation tool of this quality. That being said I have a few feature requests.
1. Call out boxes : It would be nice to have various comic/visio style call out boxes that could be use to make a comment with a tail/arrow pointing to a specific section. Similar to some of the call out boxes in the clipart section, it would just be a lot nicer if they were clean vector renders that allowed text to be aligned etc directly in them.
2. Drawing off canvas : Especially with the above feature it would be nice to be able to automatically draw off the canvas. Right now I can create an object, drag it off the canvas and then resize the canvas to fit. It would be nice if I could just draw off the canvas and have it automatically resize to fit the additional object space I have taken off canvas.