We run a home brewed login system running in excel. It successfully logs all hours from students and mentors. Its as simple as scanning your badge barcode or typing in your badge number when you come and go. Hours are then logged in the excel spreadsheet every day.
Its been in service for almost 3 years now and works with all of our teams. FLL Vex and FRC. In going through its data analysis portion, I was blown away on how many hours we put in the past couple years.
Andrew posted his system a while back as a white paper
http://www.chiefdelphi.com/media/papers/2490?