Instapaper is one of those nifty little apps that every iPhone owner needs. It quickly and easily lets you pull down web content and save it for later reading. That's nice on the small screen but think how much more use you'll get out of it on the larger iPad.
I didn't even have to wonder what Instapaper could look like on an iPad though; Marco Arment, the developer behind Instapaper, almost has the iPad version ready to go. You can read more about the iPad version and see it here. He's taking a very smart approach by setting up Instapaper Pro as a universal iPhone/iPad app so that you only have to buy it once but you'll have it on both devices. Based on what I read on his blog the iPad features are almost identical to the iPhone version, which is a lesson all iPhone-to-iPad developers should take to heart.
Since I'm going with a wifi-only iPad I figure I'll need Instapaper Pro even more than I did on my iPhone. I'm sure it will be a lifesaver every time I hop on a plane or leave a hotspot.