GifCam - An easy and fun animated GIF making application
The animated GIF below pretty much sums up how this application works. It's very easy to use.
GifCam has a nice idea where the app works like a camera that stays on top of all windows so you can move it and resize it to record your desired area.
When you're ready, click "Rec" to start recording or click "Frame" to record a single frame.
While recording whenever GifCam finds the previous frame is same as the new recorded one it automatically adds delays (milliseconds the frame stays on screen) instead of adding a new frame and increasing GIF size.