I've been using licecap in various Super User answers. It's dead simple to use as you can see from this animated GIF image - just extend it over your recording area, hit record, set a save file, do your thing and hit stop. It's free, works pretty well, and seems simpler than most of the alternatives. It's entirely free and has Windows and OS X ports.
On Windows 8.1 and hdpi displays, you'll need to turn off per app display scaling to get it to work normally without turning off global display scaling. I have a walkthrough on it here (Fixed as of version 1.26.)
BioniX Desktop Wallpaper Changer is
the most popular desktop wallpaper
changer/wallpaper manager for Windows.
It is FREE and jam-packed with
features that no other concurrent
wallpaper manager can offer!
Compatible with all Windows systems -
From Win95 to Vista and Windows 7, all
operating systems are supported.
BioniX Desktop Wallpaper Manager
supports the following image formats:
JPG (JPEG, JFIF, JPE), PNG, GIF
(static and animated), BMP, ICO, WMF,
EMF. Just drag and drop any image over
BioniX's interface and it will be
automatically included in the
http://www.online-image-editor.com/ Seems to do the job - I tested it roughly. Even has lolcats-text function :)