The WhoIsVisitor applet sends you a mail with some informations about the visitors of your site: the OS name used, and also the last visited URL which can help you to know how people come on your site.
Important notes: As applets can't connect to remote hosts, this applet connects to your local server. So your web server must also be a mail server. To know if it's true open a Telnet session and try this : 'telnet yourhost 25', for example: 'telnet www.yahoo.com 25' If it works (no errors) your web server is also a mail server. The applet size is 3x3 or something like that because the grey applet zone is no use for this applet. Note that the code used in the html file is different, because the applet must use Javascript. See the exemple file to see the code source
Extract of the FAQ:
Q) I have added the WhoIsVisitor (or GuestBook) applet to my page, but nothing happens, I
don't receive any email. Why ?
A) Before using this applet you should check that a mail server stands on your domain name server and that it accepts connections. You can do this easily with Telnet : Launch telnet (in start menu, click execute, enter telnet, click ok). Click Connexion>remote host. Enter your domain name as the 'remote host' and 25 as the 'port'. About your domain name : For instance, if your web address is something like 'http://www.thing.com/john/index.html' then the correct domain name is 'www.thing.com'. So the domain name is the string after '//' and before the first '/' (if any). Now, click connect and wait for the answer. If the server answers something like 'connection refused' or 'no route to host' then WhoIsVisitor (or GuestBook) will not be able to connect too. Otherwise, if you get a cool response then it will be ok. You can make a test: put WhoIsVisitor on your site, view your page on line and wait for the emails.