Search Engine Watch

Sullivan started Search Engine Watch in June 1997 after he posted research about search engines, called A Webmaster's Guide To Search Engines, in April 1996. Search Engine Watch was a website with tips on how to get good search engine results. Shortly after beginning in November that year, he sold it for an undisclosed amount to MecklerMedia (now Jupitermedia). He stayed on to maintain the site, and be the editor-in-chief. In 2006, it was sold to Incisive Media for $43 million. Search Engine Watch was considered by Matt Cutts, Google, as "must reading," and Tim Mayer, Yahoo!, as the "most authoritative source on search."

He has also staged the Search Engine Strategies conference six times each year, attracting 1,500 to 6,000 attendees each time. On August 29, 2006, Sullivan announced he would be leaving Search Engine Watch on November 30, 2006, he later came to an agreement with Jupitermedia to continue participating in SES through 2007.

Search Engine Land is a news web site that covers search engine marketing and search engine optimization. It was founded in 2006 by Sullivan after he left Search Engine Watch. Search Engine Land stories have been cited numerous times by other media outlets.
Search Engine Land reports that it attracted 95,000 unique users in February, 2007, representing 15% of the world market for search advertising. This user group spends approximately US$1.5 billion per annum.