Over the last few years, I've picked up a few O'Reilly books on my iPhone from the App Store. It's not particularly fun reading on an iPhone screen (especially pre-iPhone4), but the books are crazy cheap. Like £3 cheap!

I figured that the reason these books were so cheap, was that they're locked to the iPhone, and you can't read them on your PC or other device. So I was pretty made up when I realised that any (most) iPhone apps work sync to the iPad!

Unfortunately, I didn't realise the iPad would render text so nastily at double-size (I'm hoping iOS4 will fix this).

Nevermind. Today, I found a gem on the official O'Reilly site on how to extract EPUB books from those cheap book-apps we've been buying. This will allow you to read them in your browser, or any other device that supports the EPUB format. This means you can read those books in iBooks on your iPad :)

For the less technical, I've put together some screenshots showing how to do this. First, find the app in the Apps section of iTunes. Right-click and choose "Show in Explorer/Finder".

Windows Explorer (or Finder, if you're on a Mac) will open, and highlight the file for this book. Right-click and choose Copy.

Paste the file somewhere temporary, and rename it to end in ".zip".

Double-click the zip file, and navigate to the Payload folder.

Inside the Payload folder, you'll see a .app folder. Navigate into that.

Inside, you'll find a folder called "book". This is the interesting one. Right-click, and choose Copy.

Paste the folder somewhere, and navigate inside it. You'll see three items: A folder called "META-INF", a folder called "OEBPS" and a file called "mimetype". Highlight these files, right-click and choose Send To -> Zipped folder.

Rename the new folder to end with the extension ".epub" and copy it to a folder where you would like to store your books. Then from within iTunes, choose "File -> Add Folder to Library" and select this new folder. Alternatively, you can drag the epub file into iTunes.

That's it! Now your book will appear in the Books section of iTunes, and will sync into iBooks on your iPad. You can also transfer the file to other devices that can read this format.

This makes those very-attractive O'Reilly books look even more attractive!