Last night, a friend mentioned he’s been using Jing on OSX, and that there’s a Windows version available. pity there’s no Linux support.
Speaking only of the Windows version here, Jing is not quite as feature-rich as Skitch is on OSX, but it there are certain things it does better, such as selecting a window to capture, instead of, like in Skitch, having to precision-select a box around the window.

Other really useful functions, however, Jing has, where the last version of Skitch I used, didn’t. It has auto-uploads to Flickr, or to Jing’s own screencast.com. Jing can also record video in the specified selected area on-screen, so you can do screencasts and upload them wherever, including capturing of the microphone.

Jing is a magic little app, and even though it’s not something I do every day, it’s a nice addition to an arsenal of little apps that just improve every day (and not so everyday) life on your Mac or Windows PC.

And yes, Jing is free.