Here is a relatively new site that invites you to tweet about your product.
You just need to set an account and tweet away. this is great if you are a bit shy or don't have many followers. This company invites you to ride their shirt tails.
http://www.bazaartwits.comWhat is BazaarTwits?
bazaartwits lets you find, post and share deals using Twitter. It is the first Twitter-based marketplace that brings shoppers and merchants together.
How does it work?
It's really simple. All you need is a twitter account and you can start checking out and posting deals. There's a video to help get you started and there is a Faq section as well.
Good luck with it.