There is a new homepage section available : guestbook. If you enable this section, your visitors will be able to leave comments on your homepage.
You can set the number of comments displayed in the homepage section to a value in the range from 3 to 20 - the rest of the comments is, of course, always accessible via a separate guestbook page. You can also enable e-mail notification in your "My Account" tab to be always instantly aware of any new comments in your guestbook.
You need not be afraid to enable this section for the fear of spamming by guests - each guest who wants to submit a comment will have to enter an image verification code first.