I need the following simple script. Visitors should be able to enter their e-mail address in a form on my site and the address should be put in a text-file on my server. Any ideas?
Use Microsoft FrontPage to create a Feedback form with your required fields.
Right-click anywhere on the form area and choose Form Properties. Then set up the form to accept all data and store it in a text file on your server. Obviously, your server needs to be running FrontPage Server Extensions for this to work.
If that is not possible, you can achieve the same thing with CGI scripting. You can probably find some ready-made CGI scripts that will do this for you. It is a question of what server you are using and what its capabilities are.