A growing number of American chief executives rate blogs high as employee communication tools, though a majority of them remain skeptical about starting their own, a new study shows. About 59 percent of CEOs surveyed said they <A HREF="http://news.zdnet.com/2100-1040_22-5937387.html?tag=zdnn.alert">find Web logs, or blogs, useful</A> for internal communications, while 47 percent see them as tools for communication with external audiences, according to a study conducted by PRWeek and Burson-Marsteller.