I have finally joined Twitter after hearing other Etsyians rave about it. Supposedly, it is a great promotional tool. I still have no clue on how to use it but I am currently trying to figure it out. If you would like to follow me, here's my link: https://twitter.com/Jewelicide
Update: I think that I have received a few sales after joining Twitter. It has brought traffic to my Etsy sites and I have also discovered some some great artists and Etsians. Plus, its somewhat addicting.
I am also experimenting with 1000 Markets and Art Fire.