ImageWell (Free).

From the developer's website.

ImageWell is a small, but powerful, image editing application that lets you quickly resize, crop, watermark, edit your images, take screenshots and then upload them to the web, save to your computer or email them to a friend. ImageWell also lets you annotate your images with text, shapes, arrows and lines, quickly and easily. And it doesn't stop there - add a drop shadow, a shaped border, flip or rotate your image, plus so much more.

Don't want to send your image to the web? You don't have to, it's not the law. Edit your image, give it a name and file type, and simply drag and drop the image to the desired destination on your computer to save it there. Or drag and drop it into an email message, a document or presentation. Want to send other types of files to the web - you can do that too. It's easy-shmeasy, just choose the location, and drop the file over the Send button...done!

Get it here.