I just came across a really great article about websites and blogs and posts and comments and communities. Generally, 90% of readers are lurkers, 9% contribute on occasion, and 1% of readers make up most of the contributions. With blogs, this ratio is 95%-5%-0.1%. This, of course, skewers the opinions of the community in general, since only a small percentage are actually given, and leads to participation inequality.
For example, only 0.003% of users actually contribute to Wikipedia, and most of Amazon's 17,000+ book reviews are written by less than 100 people. I don't think the average joe is aware of this, its implications.
You can read Jakob Nelson's entire report here.
I myself am somewhat of a lurker, though might slot into that 9% of occasional contributors. So I guess I can't complain about the low comment rate for this blog - I suppose not everyone is a library/curling nerd.