Well, I take that back. It is slightly irritating to run Starpath's Nav Rules on an iPad. Like most all apps designed for the original 320-by-480 iPhone and iPod Touch pixel resolution, it will run on an iPad but without taking advantage of the pad's much bigger screen. Yes, I doubled the pixel count in the screens below, but Nav Rules on the iPad could easily put both the flash card and the question on one 600-by-800 pixel screen. Which would speed up my re-learning process (though of course you want the rule the question is based on to be a link away).
However, I'm quibbling about an Apple issue, really; I just don't think they're sufficiently upfront about how much better iPad-specific and Universal apps look on the big boy. In fact, Nav Rules will likely be one of the very few iPhone apps I use much on the pad. And, by the way, if the $30 price tag is a bit much for you, check out the free nav rules resources at the bottom of that product page. Funny thing: If you should happen to book passage on the Kapitan Khlebnikov with David Burch, one of the few navigation issues you won't see much of is rules of the road.