Fast and Full Featured
I was a big fan of the now discontinued FlySketch but this app has ended up being much more flexible and easier to use. You take a screenshot (options are, select an area, timed capture, full screen, previous snapshot area, your camera) and then add highlights, arrows, text, boxes, etc. I support a lot of remote users and when people have questions I find it saves me a lot of time to show them where to find what they are looking for. In about 10 seconds I can take the snapshot, add a highlight box and copy the now edited image and paste it into an email.
Evan K. 2.0 about
Skitch - Snap. Mark up. Share., v2.7.8