Recently I figured out how to make my iPad a portable pattern library, and a handy chart master. I used Goodreader, which a lot of people seem to have figured out already. If you don't already know about it, Goodreader is a dedicated PDF reader, and pretty popular with the ipad crowd.
First, I uploaded my pattern from my laptop to an online storage site, such as google docs. I opened the pattern from there on my iPad (in Safari).
I tapped the pattern center, and my iPad briefly offered me the "Open in Goodreader" button
Once I was open in Goodreader, I tapped again in the middle of the screen to view all the menu options:
On the right side of the screen, there are highlight and line drawing options which I saw quickly that I could use to keep track of such things as where I am in a chart. Goodreader wanted to know if I wanted to make an annotated copy, to which I agreed.
Now I could draw lines that I could manipulate as I worked through a chart. It was constantly accompanied by the Cancel/Done button. I ignore it while knitting and moving the line along as I go, then press Done when I put the knitting down, or leave some version of that line there to save my spot. The annotated version saves my notes, and I can add to them each time I open it if I like. There's also the rectangle option which is kind of cool.
Highlighting means that I can go through the pattern and pick out all my size numbers ahead of time.
Another feature I discovered as useful was this button that allowed me to bypass the iPad's rotating screen to fix a larger chart in landscape mode for easier reading.
I'm sure I've made this more complicated than it has to be for myself, but if you discover any tricks to add, or a way you prefer to mine, please share them in the comments.