If it’s something that your existing customers would use then market it to them.. One of the best ways is using qlippa.com
word of mouth is the best and cheapest.. The best I have seen is http://qlippa.com
If you go there and then look at the ‘Tell me how page’ they go into a lot of detail about how word of mouth marketing affects sales revenue and profitability.. Best thing is to set up your business on it, it’s free, add articles about the things you do, then invite customers to the community.. The system gives you a breakdown of your customer loyalty and gives customers a way to do word of mouth referrals for you online.. It’s cool, free, and it works.
Also, it’s a great way for a google search to find you!