If you have a young child you would like to introduce to programming, consider looking into Scratch. Scratch was developed by MIT at the MIT Media Lab as a way to teach kids (or anyone, for that matter) the basic skills they need to become successful programmers.
Scratch is a fun and easy way for kids to learn the basics of programming using snap-together code blocks to build working programs. A simple program can be constructed with just a few simple drag and drop operations. More complex programs can also easily be constructed using a variety of available programming constructs like variables, mathematical operators, conditional statements, image manipulation functions, and setting and using flags.
My 11 year old son (who has no programming experience at all) took to Scratch immediately. Within 24 hours of installing Scratch, he has already written a "Frog Simulator", building all the code to feed his frog flies when it gets hungry, exercise his frog to increase its fitness, and earn money to buy his frog flies at the store by walking his frog in the park.
Scratch 1.4 is available for both the Windows and Mac platforms, with an alpha release available as a .deb package for Ubuntu.