The personal learning network for educators
Our district use PowerSchool for attendance, scheduling, and grading. I use the PowerSchool app for iOS and love it. It doesn't take the place of the full desktop version, but makes a nice supplement. It is also great for accessing student information.
Logmein might be a soloution for you. Logmein is an iOS friendly resource for remotely logging into your desktop computer. Using Logmein is like carrying your desktop in your pocket. The app is not cheap but you can use a trimmed down version of the service for free.