I just saw that Overstock announced upcoming Twitter-only deals:
Right now Twitter is full of early adopters and tech-savvy "social media influencers". Spreading a message on Twitter doesn't necessarily reach the final customer, but it has many other benefits.
One benefit is that influential bloggers are paying attention to Twitter. Bloggers have power to hyperlink to sites. Links increase search engine rankings and traffic...
Even this guy just signed up for Twitter (!)