Calendars
Particularly for Google Calendar users, but also for those who need a good stand-alone option, is a tremendous addition to pretty much any iPad or iPhone productivity pack. Having sunk more hours than I'd care to contemplate into trying out various free and paid options to replace the stock iPad and iPhone calendars with something that handle's Google Calendar competently, this $7 app is my stand-out favorite.
Calendars handily syncs all of your Google calendars to the iPad and maintains your label colors for easy browsing through your scheduled events. And it lets you easily drag and drop appointments to reschedule them on the fly. Just tap and hold to drag them and let go to drop them. Tap anywhere to add a new appointment at that spot. Unlike the stock iPad calendar, it gives you a useful year view that shows you which days have appointments and which are free. And it gives you a week view on the iPhone, which the stock iPhone calendar doesn't. It also syncs with Google Tasks.
Taska
I don't have an exact count, but it seems like there are trillions of to-do list apps in Apple's app store, and most of them do little beyond making lists so you can check things off. My personal favorite, , comes with a fairly steep download price of $40, which makes it tough for me to recommend it here. If you want features that rival OmniFocus for GTD-style task management, check out .