A lot of what makes weblogs interesting is their personal, emphemeral, and informal nature. People can post the first thing off the top of their head (as evidenced here for the past three years), without anything in the way. If you can think it, you can post it.
That said, when a weblog comes along that takes a more serious tone, it's already a breed apart. When it's also filled with thoughtful commentary, you have something above and beyond your typical weblog.
UserNotFound.com isn't a typical weblog. It covers how online communities deal with death of their members, but what I love about it is the thoughtful essays posted by Dana. Instead of reading like a running tally of every site Dana has seen that day, it reads more like the research notes on a fascinating book. It's a fairly new site, but I can already tell she's onto something great there.