list of events and members who will join

Hi there,

I was wondering if there is a mod for the next request:

I´ve installed the calander mod which works fine. Now i want the possibility for users to let the forum know that they will join a event. Ofcourse they can write a message on the forum but what I want is a list of events and a list of users who will join the event per event. My english is very bad but maybe somebody who has a solution??