Skitch is a cool application that can work online with mySkitch–an online image sharing system. You need an invite to get a beta copy of Skitch.
With the application, you can take a snapshot on your desktop in a similar fashion to "Grab" or you can use your web cam (iSight on a Mac). You can then use simple image editing tools to draw on the file. For example, you could emphasize different parts of a web page that you have snapped a picture. Skitch will also read all the photos in iPhoto and allows you to select an image for editing.
You can then save the file and use the drag me tool at the bottom to pull the image somewhere else (Flickr Uploadr for example.)
In my experimentation I couldn’t get it to take a picture of a Second Life window, but it seemed to take screen shots from other applications just fine.
Skitch is fast, easy, and fun to use.
Written by: Creech