OK, I love the Skitch image tool and I’ve only been playing with it for half an hour. Run, do not walk to the Plasq website and request a beta copy of Skitch. This is a great app for several reasons: it is perfect for the day-to-day tasks of someone like me who isn’t (usually) a graphic designer, but do need to share images via mail and IM and do screen grabs and the occasional bit of cropping and annotating, it is totally simple and easy to use and has lots of useful pop-up tips and help, it has built in image sharing via mySkitch image hosting site, and last but not least, the user interface is AWESOME!.

This app defines broad swaths of new UI paradigms for Mac desktop apps. I love that it miniaturizes to a menubar icon - where it has a number of useful features including an excellent image grab feature. It works great with your iSight camera. All four corners of the window can be grabbed and used to resize (thank you, thank you, thank you!) It has built in image upload to a website (mySkitch by default, but set up all the upload accounts you want - FTP, SFTP, WebDAV, Flickr and .MAC). And just to show they rock and roll with Cocoa, Dashboard-style Preferences on the back of the window.
Cool as this app is to use, the main point is to improve your workflow when collaborating with others on tasks involving images. Grabbing a screenshot of a bit of mis-aligned HTML, adding an arrow with a comment and sending it off has never been easier. And for everyone building a Mac desktop app out there - check this puppy out for some excellent design ideas!