I've been using MinHub which is (for the moment) an Apple-exclusive app that is very inexpensive but has been a great tool the past couple of years! What do you use to keep track of your youth attendance?
MinistryTracker.Com is has a check-in option but it also an extremely robust CMS. It also allow teens to sign themselves in and print out a name tag on the fly. If you try to fill in out the data, it will become a full-time job so just use the functionality that you need and do not worry about the rest of it.
I've been building a bespoke youth ministry database web app since September called Youthy. You can track attendance, plan your events and rota your team. Rather than juggle different spreadsheets and rotas, Youthy brings all your key information together.
We have been using Grow Numbers Attendance Tracker. Really easy to use and offers a mobile application for check-in. Here is the link: