If you've got a kiddo who's a bit of a techie (and you're not) this one's for you. I have not personally used all of these, but I am actively investigating them...my 10-year-old has a strong interest in computer programming (specifically games). This might be a big of a challenge for me, since I don't have a background in programming (not unless you count "Hello World" on the Commodore 64---that's a blast from the past, isn't it?).
Age suggestions are relative, a lot will just depend on your child's skills and level of interest.
Gamemaker - from YoYo Games will allow you to create 2-D games without actually writing any code. Of limited educational value, though it could help to ignite some interest in the underlying coding. Some tutorials available on the site. There is a paid version of the program as well, which has more features, though we found the free version to be more than adequate. Includes an image editor (my son was able to edit his little bro's drawings and use them in a game). My son used this when he was 9.
Scratch - from MIT is a programming language designed with education in mind. The site also provides a getting started guide and other resources on how to use Scratch. My son used this when he was 8.
Greenfoot from University of Kent (UK) and Latrobe University (Australia) is designed for novice programmers to design java based games. Includes a tutorial. There is teacher support, but only for teachers with "official credentials." I'll have to find out more about that:-) Site suggests it for ages 13 and up.
Snake Wrangling for Kids is a downloadable programming course (pdf) written for use with Python computer language. ages 8 and up
Simple is a free computer programming language for kids that can produce 3-D games. Includes a tutorial. no age given
Alice from Carnegie Mellon is a program designed to teach object programming in a 3-D virtual world. Includes very basic tutorials. There are actually a number of books that have been published to teach this program. Intended for high school and up, though their Story-Teller Alice is aimed at middle school students. My 10-year-old has been successful at programming some games in this program.
Other editions of Homeschooling for FREE that might interest you:
Odds and Ends