twitter is allowing the promotional activiti. This is what I have got in their site.
"Publishing, posting or sending unsolicited email, junk mail, “spam”, chain letters, promotions, or advertisements for products or services (except where expressly permitted) is against the Terms of Service. Commercial or promotional use of Twitter is allowed, and we do welcome feed-based accounts. Many companies create valuable, opt-in relationships with people on Twitter. It's important to us, however, that the Twitter community receives only the content they'd like to receive."

You can also:: Find People by name;
Find people using keywords, location, interests, and more;

In this way we can also promote our blog/website among like minded people.