Personally, I find that while these sites are great in that they create links to your domain's main page, the thing is, they don't show up in the search results unless people are googling *specifically* for your domain. And if people are googling your domain, they are doing SEO work, comparing websites, etc. and probably not looking into the subject matter of your site, in other words, probably not your intended target audience. Google is most likely well aware of all these auto-domain-statistics sites (for lack of a better name?) and treats them accordingly.