Oh how I love my Ipad. It's really helped me write, I believe (I make dates with my writing, through the Ipad).
I also use My Writing Nook which seems to be the same thing as My Writing Spot. It works really well for me. And when they told us we couldn't connect to the net at work for personal things anymore (even at lunch/breaks - my bosses have gone crazy), I realized if I sync before I leave in the morning, write not connected, and sync as soon as I get home, it works beautifully anyway.
I also like Browser Notes (take notes while browsing or with pdfs), I have outliner but never use it (I outline on my desktop and have recently started using Scrivener for the PC). And I find wikihood and NYCWay travel apps really handy for research.
But really all I need is the Ipad and my foldable travel keyboard. The keyboard folds in half and slides in its own wallet-sized case, opened and locked it's just slightly smaller than a full-size keyboard and has all the functionality. There's only one shift key and the space bar is divided in half so it takes a bit of getting used to. But honestly, I love the thing.
And the Ipad.