I've mentioned Etsy.com a lot on this site. Despite a lot of disparaging remarks ive heard about etsy and indie crafts and low brow art, I'm a big fan because it has been a great pipeline for experimentation for me. By creating itself as a marketplace for things handmade, it has allowed a super high volume of people to see and recognize my work. Generally i only list my smaller pieces, but this has lead me to play more with various approaches to my castings and plaster work.
It has inspired series of pieces that i've shown and sold at festivals and fairs. Venues such as Crafty Bastards and Adams Morgan Day, Arts on Foot and various other events. Due to this approach i have felt a deeper connection to my city and community than simply exhibiting at Galleries.
Recently i learned about Poppytalk, and just today was featured as their Etsy Pick of The Day! exciting! Also cool is that one of Rania's pieces is their icon for their art buying guide!
I was also accepted into the Trunkt.com listing of artists designers and craftspeople.
These types of sites have really helped artists such as myself get their works seen, and sold.