While frozen meatballs can certainly be used for Spaghetti and Meatballs, there are so many more uses for them... and they don't necessarily need to be dinner entrees.
Swedish Meatballs (appetizer)
Italian Meatball heroes
These are just a few options. I've even seen an appetizer recipe that involves a bottle of chili sauce and grape jelly... and it's not as gross as it sounds. It turns into an interesting barbecue sauce once combined and cooked.
While I wasn't able to find that exact recipe (I think I saw it in one of those church fund-raising cookbooks my grandmother has) this one is darn close: