I just discovered Skitch yesterday, and I'm already loving it.

Basically, Skitch is an uber-screenshot application. So, you use Skitch to take a screenshot (or just drop a graphic into the Skitch display), then you can do all kinds of editing to it, upload it for sharing, copy it to your desktop, drop it into your IM client to share with a friend, or any other number of things.

Yesterday it came in handy when I was trying to show Bob something I wanted change on the elemental life site. I took a screenshot with Skitch, dropped it into Adium, and off it went. Then, today I've used it on both of the images I've posted. I uploaded both into my Skitch page, selected the share option, grabbed the image code that was all ready to go, and put it in my entry (I did have to tell it to right align).

Here's a video with a bit more on Skitch: