I've found that the social networks, while they do work, have only been so-so for me personally. My best marketing has come from advertising specials and giveaways on websites like http://www.indieshopping.com/, http://www.modish.com/ and http://www.indiepublic.com/.
Indieshopping.com and Modish.com both have prize package giveaways each month and if you send in one of your items and they choose it for a giveaway, your name and link is mentioned on their website.
Indiepublic.com has a contests and deals page where you can list your contest or sale for free. It has been a nice tool for me to get visitors.