Algebra is for ?

My ds is ready for algebra and I've been checking out curricula to order. It's already March and school is out in just a couple of months so it's time to decide if we'll school year round or not. He'll be horrified and feel totally betrayed if so. He's home schooling so the public school schedule has nothing to do with him really. I really have to decide right now, or at least in the next couple of weeks, if he's going to public school next year. There's really no need, he's doing fine here. I worry because he is totally NOT a social person. At school in years past, he always made friends but refused to bring them over to our house, refused to go to their houses, didn't want to invite anyone along when we went to parks, lunch, anything.
The best thing really would be to find like-minded kids to get together with on occasion, kids or adults actually, who are interested in science and math.
Anyway, back to algebra, I always enjoyed algebra and geometry in school but I have never had occasion to USE it. I realize that algebraic thinking is probably interwoven in much of life, not something we specifically think about, but I'd like some examples to show my son of why we learn it. It will be much easier to find something for him because he's much more comfortable with numbers than anything else, but I can't think of anything. Anyone have any ideas?