Byzanz!

This tool allows you to record a selected area of your screen and save as a animated gif.

LICEcap can capture an area of your desktop and save it directly to .GIF (for viewing in web browsers, etc) or .LCF (see below). LICEcap is an intuitive but flexible application (for Windows and now OSX), that is designed to be lightweight and function with high performance.

GifCam is a handy and reliable application designed to record the screen and to convert the recordings into GIF format.

Gifox is a beautifully designed and masterfully crafted app that records your screen into animated gifs – the great alternative between static images and full-size videos. It's your best companion for:

Gif·gIf·giF (ggg) is a small shareware program for producing GIF animations from screen captures. It is especially useful for producing animated software demonstrations or tutorials. GIF animations produced with Gif·gIf·giF are automatically displayed by web browsers, such as Netscape Navigator and Microsoft Internet Explorer, without requiring any add-ons, plug-ins, or helper applications.