Blog readership has risen dramatically this year as the number and reputation of blogs spread, with unique visitors to the top 50 blog-related sites up 31 percent in the first seven months of the year, according to Nielsen/NetRatings. By July 2005, blogs boasted 29.3 million unique visitors, amounting to 20 percent of active U.S. Internet users, the survey said Monday. Blog hosting sites, which have spawned millions of blogs, play a key role in the spike in current blog readership. Blog host sites require very little technological knowledge from bloggers and their readers. MSN Spaces, which came out in beta...