Facebook has helped me tons....I can get my work out there, for free, to a large group of people. I always do "sneak peeks" (as long as the customer is ok with it) on facebook, and "tag" the customer in the photo. That way, it links their friends and family to my business, and gets people poking around on my business page!
I've gotten more sessions that way....from people I went to elementary school with and haven't seen in 20 years, from their friends and family, etc....
I also volunteer my services a lot.....help out the local YMCA shooting photos of their event, or things for the local school district.....lots of charity stuff. It's for a good cause, and it makes my work more visible!