How do you make your iPad productive?

I've had a fair amount of experience trying to turn the top media consumption device into a work machine. My school gives out iPads to all the students, and initially it seemed like a wonderful way to go paperless and cut some weight from our bags. The only problem was that being productive meant working around the iPad's limitations, instead of embracing its functionality. But where is it? Where's the killer apps, the sweet features, and the slick accessories that turn the iPad into a work machine?

They gotta be out there, so here's where I consult you, Core.

In my experience, Notability was the most useful productivity app I could find-- which still didn't feel great to work with. What other apps do you use or know of to make your iPad productive?