Currently you can check-in (take attendance) at a Group level and/or via the Rock Check-in system.  It would be great to have a similar option on a Registration.  For example, when students register to go on a camp or retreat and are required to Pay for it as well as complete paper work such as Parental Permission slips and Medical Release forms, it would be good to have a 'Check-in' tab maybe on the Registration itself that displays all registrants along with their Balance due and any Registration Attributes that are set to 'show on grid'.  When a student arrives to the camp to 'check-in', this information is reviewed and any outstanding balance and/or paperwork due are collected. This screen would then also allow them to mark them as 'here'.