MicrostockGroup

how to do you mean.. like name / email address?  then no.

With google analytics or similar you can see the 'profile' of people who read your blog, like how many people, where they are from etc.

That sounds a little spammy yeah.  What blogging software are you using?  On wordpress you can see the email of people who leave comments (if they give their real email that is)

I'm using wordpress, in my website.

I can see an email (real or fake, who knows) of the person who left a comment, but I can't see if he is a feed subscriber or not. Some spams link to commercial and porn sites, and these I mark as spam, however there were two recently comments whose links seem personal, but I'm not sure and I haven't approved them just in case. I received comments from strangers, but often asking questions about the lovebirds, and these I approve. These two suspicious ones are very generic messages ("very good information" and phrases like that).