With a good API I could think of lots of things that I'd personally use this for. I, for one, like having a daily list of tasks I need to accomplish on paper that I can have with me (I know I have my cell phone, but something about that physical copy just makes me more proactive in checking it and getting those items done).

Also, I coach my son's basketball team and before every practice I'm making out a practice plan (currently just in a notebook), but that would be nice to store them online, easily modify, then print before practice.