Large advertisers have been doing it for years – buy our product and get a free t-shirt to wear around and help spread the word about our company.

I love this type of grass roots promotion and I think small businesses underestimate how a well run promotion involving every customer can turn into a flood of buzz and referrals. I’m not talking about some of the once trendy “paid to drive” type of schemes, I’m talking about ways that small business owners can get their customers to spread the word.

Here’s an example I witnessed this week.

An auto dealer offers car buyers free oil changes on a schedule for as long as they keep a simple website address decal on their back windshield.

This is just a twist on the age old endorsement tactic, but by doing all the work for your customer, creating the bumper sticker and offering an incentive, you get immediate benefit. Cars are a great vehicle (I know) because they move around like mini billboards, but so do pizza boxes, flower arrangements, real estate signs, backpacks and bikes.

The key is to offer an incentive that makes people talk – free oil changes for life might do that and is in line with your overall brand (it’s pretty easy to go overboard and actually turn people off – know you customer!). Make the incentive about your products and services so you can continue the relationship with your client and highlight a feature of your business that they may not be as familiar with.

So, what creative exchanging advertising for services have you seen, offered or experienced?