I just finished doing this so I do not know what the results will be but its free to do and takes only a couple of minutes so it is well worth trying.
From Randy Smythe's "My Blog Utopia":
I'm trying a little experiment over on Twitter, why not join me and spread the word. It is called #ShopTwitter.
What is the experiment? Basically, I've created a Twitter thread for online store promotion. I have no idea if this will generate any sales, but it’s free so it’s worth the effort. The idea is to expose your online store to millions of Twitter followers in one simple list.
This is not the same as Twibbler and you should only promote your stores, not individual listings. Please only post one tweet for each online store.
Here's what you do:
1. Setup an account on Twitter if you haven't already. It is very simple and you won't be able to participate in the promotion unless you setup the account. Don't worry about learning Twitter right now, you can learn what you need to know just by following these instructions. This link will take you to the Twitter sign-up page if you need to sign up.
2. Once you have an account, type a store promotion tweet into the comment box underneath "What are you doing?" that ends with the word "#shoptwitter"
Here is an example:
Bonanzlemark – Vintage items 25% off use coupon code: "Bonanzle" at checkout http://www.bonanzle.com/booths/bonanzlemark
If you have a coupon code, add that as well. You only have 140 characters, so be as concise as possible. Start with your booth name and then a short description including important keywords. Don't forget to include the URL of your store. You must include the string "#shoptwitter" in your message to get in the list! Don't forget that detail!