You can add a survey to have the members of your agenda introducing themselves.
Here is an example :
Those informations are private. Solely the administrators and moderators will have access to it. Only them will also be able to exporte them.
This action will gives you an index of the people registered on your agenda.
To activate it, click on "Manage" on the agenda of your choosing.
Then in the tab "Customize", click on "Contribution".