Bocce ball set Depends on what they're made of. The metal ones could be melted and shaped into knives, arrow heads, etc. Metal pieces are also good for attracting birds during hunting, to get them within range.
Plastic balls could also be melted and used as coating/paint, knife handles, cordage, string for instruments(CDs make nice picks/plectrums!), maybe fishing wire? If they float and are brightly colored they can be used for holding up fishnets.
Wooden balls can be carved into cups, containers, etc.
Plus, of course, ammo for slings.
Now, what useful could be done with that evil invention money?