From DMNews.com
What you should do. If yours is a large company, policing all your trademarks in all their online search contexts could be an overwhelming burden requiring near-infinite resources. However, there are concrete steps any organization needs to take to proactively defend its trademarks.
o Implement a complete organic SEO campaign on your site to protect the free organic space and compete with the costly paid listings.
o Create a cease-and-desist policy to enforce your rights when a violation of your trademark occurs.
o Put a strong statement of your trademark protection policy on your Web site and provide a place for people who have been led astray by a violator to report the violation.
o When creating an affiliate agreement, include a keyword do not purchase list covering trademarks.