I think I tampered with a commandment or two when I saw the Ten Commandments for Writers, by Barbara Dawson Smith.
Ms. Smith talks mainly of writers, but what she says may well apply to bloggers.
I. Respect for thy fellow bloggers is the Lord, thy God, and thou shalt not worship the false gods of fame and fortune.
II. Thou shalt not take the name of a fellow blogger in vain.
III. Remember to keep holy thy blogging days.
IV. If some publisher picks up your online work, Honor thy editor and thy agent.
V. Thou shalt not kill thy neighbor's ego while critiquing her work, though purple prose may be slain at will.
VI. Thou shalt not allow thy hero or thy heroine to commit adultery.
VII. Thou shalt not steal plot ideas or words from thy fellow authors.
VIII. Thou shalt not bear false witness against another author by spreading gossip or by criticizing her work to booksellers and reviewers.
IX. Thou shalt not covet thy neighboring author's husband, even if thine own refuses to support thy work.
X. Thou shalt not covet thy neighboring author's contract, nor her place on the New York Times bestseller list.