Every student's main preoccupation, besides parties and budgeting, are definitely grades. The time spent by many students trying to estimate their passing minimum often tends to equal to the actual preparation time, an often necessary, but unfortunate situation.
A student named Jeremy Olson realized this and undertook what many have done before in this kind of situation, make an app for that. The result of his work, the Grades - Roadmap To An A app was released to the App Store today to help accomplish this tedious task.
Thanks to a simple interface, Grades allows you to keep track of all your grades and most importantly, it will compute what is the minimal result you can afford to get on every single exam. You're free to set your own target grade (90 by default) to better manage your expectations and you're good to go.
It's still a working project as the app can't calculate transitory results, or let you drop the worse grades yet, but this should be added in the app's next iterations.