Some weblogs are really just private diaries intended only for a handful of family members and close friends. Usability guidelines generally don’t apply to such sites, because the readers’ prior knowledge and motivation are incomparably greater than those of third-party users. When you want to reach new readers who aren’t your mother, however, usability becomes important. —Jakob Nielsen —Weblog Usability: The Top Ten Design Mistakes (Alertbox)
I would only add that, while Nielsen’s points about uninformative link titles are sensible, sometimes it’s a rhetorical choice to link to an off-site source with a single word, or even a single letter, rather than always writing out a whole sentence or using the whole title of the off-site page. But the general point about writing for an audience that’s new to the conversation is a good one.
Blogs can be too chummy if you consistently refer to other bloggers with their first name, but I figure if I don’t recognize the name, I can always mouse over the link and check out the URL that appears in the lower left corner of the window. Since I’m more familiar with the names of some blogs than the names of the bloggers, that’s usually enough to help me place the name.