Ha...I know exactly what you're getting at.
The current version of Events doesn't allow for that, but it'd be a CB plugin that builds, queries and outputs data from a new table associating two indexed fields: a Joomla user id and an event id. Maybe a field for comments would round it out. A feature like that could be built into this plugin: it's just a question of interest.
The only problem is how to get the "Add to my events" button in the calendar, or in the event detail. It'd either need to be supported in the component itself or maybe with a plugin (mambot) that includes it before or after the output.
Apparently you can do this with Attend Events and the CB plugin, but it's a little clunky in that each "sign-up" needs to be handled manually.
Joomlapolitan zealot and a somewhat stealthy, rather passive CB3PD developer.
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