With Zoho Site, the users can create a blog. Visitors can post a comment on the blog.
However, there is a issue about compatibility: visitors can not post a comment on Internet Explorer.
Website (including blogs) is built for all visitors, and the user can't specify visitors to must use browser what can leave a comment.
I think this is not a friendly design. It should be compatible with most major browsers (Chrome, Firefox, Internet Explorer, Opera, and Safari).