Screencapture with built in annotation features.

Mac OSX has built in screen capture functionality (shift-command-3 and shift-command-4), so why bother with a screen capture app like Snip? Well, the reason I like snip is that it has built in features allowing you to add circles, boxes, arrows, pen and text to the screenshot before saving it. Sure, you could use shift-command-4, then open the image in Paintbrush or other image editor, but that adds an extra step. Snip is fairly lightweight (I have the Activity Monitor open and it is only using 13 MB of memory), so there isn’t much of a performace hit to keeping it open.

KeithK3 about Snip