Did you ever think about possibly attaching balloons to the mailboxes of customers who have children every once in a while after you service their property? It could be a great way to stand out, Maybe you could even attach a referral gift card?
Or what if you marketed that you could either rent or sell helium tanks for birthday parties and events? It could open doors to other business ideas like renting tents, tables and chairs in the future. How about even big bbq grills?