Many states require all high school students to have at least one year of foreign language study. There are many possibilities for pursuing a foreign language. Rosetta Stone seems to be very good, although it is expensive. There are websites online, like Live Mocha, that offer free classes. Other websites, like Digital Dialects, offer tools and games to add to whatever curriculum you are using.
Arts and crafts add fun and excitement to any school day. There are many ideas for crafts online at Life Tips, A to Z Home's Cool Homeschooling, and ABC Teach. Art is normally done once a week. Have fun with it!
Some states require students to have a certain amount of physical education per week. You can check the law for your state on the Homeschool Legal Defense page. Even if your state does not require it, it is still fun and fulfilling. You can create your own P.E. plan (There are many ideas for physical education listed HERE.), or enroll your children in gymnastics, karate, or any other number of programs. P.E. is usually done once or twice a week.
Music is not usually a necessary requirement to graduate, but it is beneficial. Learning music helps build the brain. "Music" can be accomplished through piano lessons (or learning any other instrument), enrolling them in the children's choir at your church, or giving lessons yourself on the mechanics of music.
I know there are other extra-curricular activities out there, and I am sure you can think of a few :). these are the ones we include in our school days. For are learning Spanish on Mondays and Wednesdays. We do Art on Tuesdays, Karate (which is our P.E.) on Thursdays, and piano lessons on Fridays.
Do not go crazy with your extra-curricular activities, but do have at least a few! The idea is to add fun to the school day with something that will be beneficial in life. Be careful not to over-do it, or your school day will be so full of extra activities that you may not be able to complete your school work for the day!
What kind of extra-curricular activities do you do for your children?