Do Top Lists have value?
Radio has at least three public pages that show top 100 lists.
These types of listings are sort of self-fulfilling if users visit them to find sites. Once a blog is listed on a top list, it will likely get additional referral traffic from those pages and then possibly subscriptions and/or bookmarks which helps reinforce the popularity of the blog.
When I was still doing City.Net (Excite Travel, now defunct) we made a list of the most popular cities based on web log traffic. After that list was made public on the site there was very little variation to which cities appeared on the list, only slight variations of the rankings of the cities on the list. People were using the popular cities page to navigate directly and appeared to spend less time just browsing or searching for alternative destinations.
In Radio blog terms this means that the entrenched sites that already have a lot of blog rolling going on will likely stay in the top 100 and as the Radio community installed base increases, the new blogs will have to play catch up.
Perhaps the traffic numbers don't really matter except perhaps as ego enforcement for the most popular sites or a discouragement to new bloggers that expected to suddenly be popular. Or is all this just a form of voyeurism? I have to admit that I find myself drawn to the rankings, which might be due to my former life at a web startup where traffic was everything.
Then I have to remind myself that the actual traffic is so small that what the numbers really show is how little readership even the most popular blogs (at least in the rankings above) get compared to entrenched name brand sites. When you compare a commercial site that gets a million page views per day, say roughly 700 page views per minute versus a blog getting 700 page views for a whole day (on a good day) it shows that blogs have a long way to go to get the same kind of reach as a name brand publication. Of course, it may be that writers like Dvorak get a very small fraction of the millions or tens of millions of page views that ZD gets each day and that writers for the New York Times have less web readership than something like Scripting News. But I don't have a Top 100 list to point to for the answer. :)