Not knowing your son his learning style and his talents it is difficult to recommend specific learning products. However, remember that time is on your side you do not have to jump into a curriculum package or specific course of study just yet. Children often need several weeks or months to "detox" after leaving school. (See Leaving School and Learning at Home.) Enjoy this time together and help your son rediscover his interests and develop new ones.
Turn off the TV and put away the GameBoy for a while. Visit your library often and take out books and tapes on a variety of subjects. What does he like to do? Skate-boarding? Karate? In-Line skating? Does he have a special interest? Bugs? Animals? Tornadoes? You'll find beautiful, detailed books on all of these subjects. You don't have to read them all they can be used as a springboard for further study. Go home and look through some of the books with him. Don't make this into a reading assignment just make sure the books are available to him, and read with him each day. See what sparks his interest and follow up on that subject. Does he like that book on ants? Maybe you can buy a small, enclosed ant farm. Rent a National Geographic video on leaf-cutter ants. Observe the different types of ants where you live. You'll quickly discover that with a bright boy like your son, this type of activity (whether the subject is ants or airplanes or the stars) will encourage further explorations into self-directed learning.
After you've both had time to adjust to your new homeschool lifestyle, you may begin to incorporate structured learning activities. To learn about the different curriculum choices available to homeschoolers, read Choosing a Homeschool Curriculum and Homeschooling Isn't One-Size-Fits-All.