Calendar plugin help

I am looking for a calendar that will allow TWiki users to log into the site using there account and update their own calendar. I have used the Calendar plugin but this seems to put all events together from all users, rather than each been able to have an individual one.

I would then want to have one that gets data from everyone’s individual calendar and puts it into one. (This part I will hopefully look at sorting out myself)

Just would like some advice on which calendar allows individual calendars for each user? I was using TWiki and was able to do this but not sure if it can be done in WordPress as easily.

Thanks