Is there any way to create a form that displays the information generated by the visitor for other people to see and possibly add to… like a sign up list for an event that grows as visitors to the site add their name?
You could look on HotScripts for a guestbook application that will run on your server. Most hosting providers have one or more dynamic languages enabled on even the most basic packages. Check there first what you can use (PHP, Ruby, Perl, etc.) then look for a script to do this. (You may even find that your hosting provider has already installed one or more of these, and all you have to do is use it.)
What you describe here is not difficult, you wouldn’t even need a database for this, you could simply modify a plain text file since all you’re doing is adding names.