I got my first iPad in the summer of 2010. You may or may not know that I work in the publishing industry. I told myself it was research for my job because we'd be selling more ebooks and I wanted to know what the environment was like. That made for an awesome excuse. Now, I'm on the iPad 3 and I really just love it. I read on it almost every day I read a few magazines on it (Martha Stewart Living is actually one of my favorites!), play some games and knit with it. Yup. That's right. I knit with it. Since I knit with it so often, I thought I might let you in on the apps I've used and which ones I like best for knitting. All of these apps are available for iOS devices, but if you have an Android device, I think some of them are available for those as well. I know Dropbox is at least.
ibooks - Free! - I almost exclusively read books on my iPad now. I'll only really ever get a physical book if there is no ebook available. That means that often, my knitting books are pbooks instead of ebooks. I've found this is a great way to hide my book stash from my boyfriend. However, I've also found that when reading pbooks, I tend to try to highlight words I don't know to define them. That functionality really doesn't work as well in a pbook, by the way.
I actually haven't been using iBooks for pdfs of patterns at all. I will use it for pdf ebooks like Ysolda's Little Red in the City. I can highlight and add notes to things I find important and keep bookmarks of things, but for patterns, I find there are other apps that have better tools to help knitters.
Goodreader - 4.99 - You can get a free version of this app, but trust me, the $5 you spend on this app are WELL worth it! It's best for pdf files, I have had some trouble with using word files. Why is it awesome though? Do you knit shawls? You do? BAM! make a line and drag the line up the chart. You know exactly what row you're on and what to do on it. Add a note to let yourself know how many times you've done that repeat of the pattern. I'll bet that sweater you're working on has multiple sizes right? Highlight the instructions for the one size you want to knit. You can add arrows to point towards directions in written patterns to let you know where you left off. It's pretty sweet. You can transfer patterns onto Goodreader from your computer if your device is connected, or over wifi. You can synch Goodreader with your Ravelry queue (via the instructions here). Or you can import the files from a cloud service.
Dropbox - Free! - Dropbox is definitely my cloud service of choice. They start you off with a certain amount of space, but every time you refer a friend to their website and that friend joins up, you both get more space. I put music, photos, patterns and all sorts of stuff on there. If I want to share anything, I can send a link to someone so they can access just that one file. You can also use it to review patterns and things like that, but it doesn't have all that functionality of Goodreader, so it's good for reference, but not so great at keeping track of where you are in a pattern.
Knit-N-Count - $2.99 - I've used a few different counters. For a while, I was using the StitchMinder app to count rows. But when I started using two counters of the four counters StitchMinder provides to you for one project, I thought that might not work for the long haul. In Knit-N-Count, I can name projects, keep notes on them if I want (I've actually copied in a whole pattern for a simple sock before and used that instead of goodreader), all in addition to the counter. This counter is actually quite sophisticated for a counter. You can set alarm rows, repeat rows, pattern repeats and it'll keep track of your total row count as you're doing all of that. Make a mistake or accidentally press the row button one too many times? No problem, hit the frog button and the counter goes back a row AND makes a "ribbit" noise!
Those are the key apps I use to knit with on my iPad. I also read Vogue Knitting on my ipad (from the Newsstand) and if I want to grab an Interweave magazine, I'll nab it off their website so I can import it to Goodreader if there's a pattern I want to use. You can get IK from the Zinio Magazine app, but it's not a pdf, and oftentimes they're slow in adding things to Zinio.
I used to make a copy of a pattern from a book so I wouldn't have to lug the whole book around with me. I'd put it in a sheet protector, and when I was done with it, I'd stick it in a binder. Now, I scan the document into my computer, pull all the pdfs into one document and load it up into Goodreader. There are some books that doesn't quite work for. I bought Cookie A's Knit Sock Love and the size of the book made it quite difficult to scan the pattern in from my home scanner (with legal sized glass) as well as work's scanner (more like a tabloid sized glass). I ended up typing the pattern up in word and bringing it into Goodreader like that (which is how I know you can't really edit any word documents in Goodreader). I'm not sure what I would do if I needed to do something similar for any of her other patterns that are more complicated or included a chart. I'll cross that bridge when I get there.