utilities to know connected users

[silvo conticello]

Does anybody knows utilities that show the connected users (CLI: 'who' 
or  'last') in the  the Menubar?
Or even better, some application that produces some kind of alert 
whenever a user logs in?

Thanks,
Silvo

Silvo Conticello
Albook 17" 1.5GHz/1.5Gb RAM/80Gb HD/OS10.3.4
iMac 1GHz/500Mb Ram/80Gb HD/OS10.3.2/17" display
E-mail: silvoc at tiscali.it
Cambridge
UK