Does this family live near a great zoo? A children's museum? How about a YMCA with free family activities and classes? A year-long membership to these types of local attractions will be used and appreciated year-round.
This is one of the best gifts our family has ever received. Our children were given 'gift certificates' from my parents for any lessons they would like to try. It was a wonderful adventure just seeking out the different types available: ballroom dancing, water polo, piano, guitar, rock climbing, martial arts, gymnastics, ballet and horseback riding were a few that were seriously considered. One of my children is, three years later, still participating in the original activity he chose.
Homeschool families love all things literature. Just make sure you are considering the ages of the children when you make your purchase. Most sites online will have recommendations by age. Nonfiction is going to be preferable - you can even ask the families what they have been studying recently. They will appreciate your interest as well as your investment in and support of the lifestyle they have chosen.
Homeschool families LOVE a good field trip. Is there a fantastic place they would love to go? An air and space museum? A mine of some sort? An historical marker with attractions? Find a way to help them go, whether it is passes to the location itself, a place to stay while there, or a gift certificate to a nearby restaurant.
5) Magazine Subscriptions
There are mountains of wonderful publications in circulation for all age groups of children. You will want to be sure you dig a bit before you subscribe - often the most popular magazines are not the meatiest. Homeschool families are going to prefer very high-quality content, and they will thank you for it every time it arrives in their mailbox.
What is the best gift you have given or received that pertains to homeschooling?