Provide the option to add an event after it has occurred - sometimes we have adhoc/ pop-up/small group activities that turn out to be much bigger than expected. For reporting purposes it would be useful to be able to add these and mark attendance. There is a work around for this currently - If you create the event using today’s date/time and set the ‘Show After’ date as a date in the future - however the date and time of event is not accurate in the report.
I 2nd Adam's comment below, add it on, cannot book on, add attendees mark as attended/passed. Its just data collation for event programmes and report apps.
I already do this all the time - I set a date in the past - and turn off "enable registration" on the Registration Details page. Then register all the users (it doesn't email them an invite for a past event if there's no custom email set up) and then mark them as attended and it completes and all done.