I am an introvert by nature which by the same token, one with few people I can call friends to do any word of mouth with which I have covered that base quite well. Family, on the other hand has no use for web hosting and would tell people they know if they are looking for hosting to go through my service.
For the sites I have produced for clients, they are hosted by me and have a backlink at the bottom pointing to my services, but with the traffic which comes from there, not a single order. I am at a disadvantage in my hosting at the moment and am about to restructure it to be more of a unique hosting service but not until the weekend maybe. Once I do that, I will be starting to do advertising more. I have one awesome customer who has referred one client to me which later left my services, but is half way back to me paying for a service that complements his hosting. The same client that referred is working on referring another client to me.
I do have a deal with every client that basically gives them some money back each month for referrals which has motivated some but not all. Being small is a pain in the neck sometimes, but nice at the same time. I am personally wanting to have enough income monthly to pay for my overhead (licensing, hosting fees, etc) and maybe a tad more. I know I can't compete with the big dogs out there, but I also know with longevity, it can really build trust as well so you know you aren't dealing with a 'fly by night' hosting company that we all hear about on WebHostingTalk.