More than a year ago I queried agents about representing a novel dealing with stuttering. I got some partial reads and some suggestions, but no takers. In addition to continuing to work on the novel, I also started a blog for persons who stutter. After a slow start, the blog traffic has picked up substantially, thanks mainly to some mentions in speech therapy publications. The blog is in the Miss Snark format -- readers ask and I answer. (While my passion matches Miss Snark, my wit certainly does not.)
Question: Would the blog help validate me in anyway? Should I mention it in my next round of queries?
Validate you how? That you have tons of readers? I think editors are looking for pretty serious numbers of hits for that. I asked the cigar smoking Beatrice about this once, and he mentioned even his hits weren't considered all that great (and he was pretty much THE blog about books at the time).
Validate you for content? This is a novel. Your writing has to stand on its own.
Validate you for being witty and charming? Perhaps, but man oh man, you better make sure your shoes are polished and your mohawk is freshly purple and pointed if you're inviting guests to drop by any hour of the day.
I don't think it's nitwittery to mention you keep a blog, but I also don't think it's a big selling point either unless you're getting those gazillion hits mentioned above.