Instapaper is a simple application for the web, Mac desktop, iPhone and iPad that stores websites for offline view data, even optimising the content to be friendly on whichever device you are using to read. This works similarly to RSS readers like NetNewsWire which stores content offline, except where RSS feeds only store the headlines, this stores an entire web-page. It remembers where you read up until and you can switch devices and read where you last left off. Now, this has been quite nice on the iPhone, where you use it in conjunction with NetnewsWire to store the content of a web page (which you found off a feed) for viewing in an easier fashion, minus all the layout hassles.
Now with the iPad emerging from the labs at Apple to our hands, deciding between having a more pricey 3G enabled iPad and a normal Wifi iPad, can be made easier when we have InstaPaper, as you can store at home websites you are interested at looking at, and when you are on the bus commuting to work every morning, read your pages without having to fork out to your network carrier money for doing so, when you already do that with your iPhone.