An article by PC World looks at the use of Twitter's search tool to promote websites and brands.

At the very basic level, the micro-blogging site can be used to search for mentions of a company name or brand, and then following those users or responding to them directly in an appropriate manner. However, smart marketers are also using Twitter to search for more generic words or phrases to find potential customers and then contacting them with valuable information or offers that might be of interest.

Twitter users tend to be more responsive to this type of approach, although if the practice becomes more widespread or abused, that particular channel could be closed. There are also new services appearing that try to automate this process, such as Replyz, which the article says aims to make it easy for marketers to find relevant questions that Twitter users are asking.

Marketers can also use Twitter APIs (application programming interfaces) to create tailored tools to monitor Twitter queries and automatically send direct responses to people, or to constantly monitors trending topics, looking for matches with keywords important to a company.