Check out this post from Copyblogger:
One thing that blogging and good copywriting share is a conversational style, and that means it’s fine to fracture the occasional rule of proper grammar in order to communicate effectively. Both bloggers and copywriters routinely end sentences with prepositions, dangle a modifier in a purely technical sense, or make liberal use of the ellipsis when an EM dash is the correct choice—all in order to write in the way people actually speak.
But there are other mistakes that can detract from your credibility. Read the full article.
(from: Five Grammatic Errors that Make You Look Dumb)
