Actually, I don't want to resize as in making it larger or small in general, but I actually want to extend the canvas by pulling on one edge or another. I often use this to create new area to draw on or to add extra background around the image since it adds space based on what's at that edge. For example, I can take a logo that is cropped closely and give it a buffer around the edges.
In the old Skitch I could grab any edge of an image and drag outwards to extend the image in that direction. I found this very useful -- VERY USEFUL. In the last version, I find that I can no longer do this. Am I just missing the right incantation or is it no longer available now that Evernote owns Skitch?