There are several things a person might like to include in their guestbook. That is all a matter of personal opinion. How the information is displayed to a user is another matter. Through the use of menus, buttons, and different boxes, a person can easily create an interesting guestbook for users to sign.
Radio buttons act like that of an old car stereo.
You could push a button to tune in one station, but push another, and the original station is gone. Same goes for radio buttons. One can be clicked, but only one. Next we have Checkboxes. Checkboxes are another clickable entry, which unlike Radio buttons, allows a user to check more than one of the items.