Listen: the term "blog" is a hideous, dysphonious neologism, a linguistic travesty, a ragged scar on the weird but beautiful English language. Its sole saving grace is that it's arguably onomatopoeic: it sounds like violent emesis. Worse, like any disease, it's spreading; witness "blogger" (the name of this very service!) and "blogosphere."
I admit that English is in a state of disrepair that makes this particular concern seem picayune, like filing your nails while you bleed to death. But to reverse the damage, we must start somewhere. Surely we can coin some relatively mellisonant term for these things now called "blogs." Anything I invent in my current snide mood would be dysphemic, so I won't pretend I can do it now. (I tried, but my first thought was "e-pistle"; I recognized the despairing sarcasm and shut down that line of thought instantly.)
Looking ahead, once we nominate a successor, we'll need to dethrone the existing term. I think the most effective approach will be to shame and ridicule those who say "blog"; this has helped rid us of the tiresome "cyber-" prefix, so there's hope. (Or, if not effective, at least it will be a sort of petty, snobbish fun, which makes a decent substitute.) We can lay the groundwork now: when you must say "blog" or one of its derivatives, do so as if you're not so much saying it as vomiting it. Whether you do this in mixed company is between you and your conscience, but keep in mind that it's one of those small ways we can all work together toward a better tomorrow. By which I mean, specifically, a tomorrow without the word "blog" in it.