7. Thou shall not use aliases or sock puppets. If you have to invent a separate identity in order to create the illusion of agreement, then perhaps your point isn't as good as you think it is. Although it's tempting to play games with the pseudo-anonymity the Internet provides, it's far better to stick with one identity.
8. Thou shall not feed the trolls. When people spew insults, pick fights, or take contrarian positions just for the sake of being contrary, ignore them. Insulting online miscreants or engaging them in arguments accomplishes nothing, it just further pollutes the pages with pointless back-and-forth.
9. Thou shall resize thy images. Remember, not everybody has screamingly fast broadband connections like you, and not everybody has the patience to wait for that huge picture of your pet iguana to download. Plus, margin-breaking pictures are just plain annoying.
10. Thou shall respect the old adage: What happens on the wiki stays on the wiki. It's wonderful how blogs and wikis can provide you with new knowledge, insight, and perspective, and you should certainly carry what you learn with you when you leave your computer. But all the bickering, arguing, correcting, and other antics it took to get there? Leave those behind -- no need to bring your wiki-capades home with you.