Instapaper is a service that stores web page content for offline viewing. The iPad app for Instapaper is really nice and has good integration with apps like Zite. The steps for making Instapaper work with the Safari web browser on the iPad are not too difficult. A shortcut needs to be created and edited, with the name changed to something like Read Later and the URL changed to a JavaScript link in the Instapaper set-up instructions.
When I traveled with my new iPad 2 and was in the air without Wi-Fi, I had not saved enough content to read on the trip (not enough modern content, because I did have e-books loaded).
I'm using Instapaper a lot now when I want to be sure to save the content for later reference. It seems more certain than just a bookmark, but I'm not sure how the Instapaper content may be updated or deleted based on what happens to the original source; I don't have enough experience to know.