I will add my 2 cents for the iPad as well. I have been using it for almost a year and cannot say enough about the utility of foreflight on the iPad. While goodreader, etc... are cheaper solutions, keep in mind that not only does foreflight offer charts. They also offer radar/satellite overlays on your route, fuel prices, etc... All of the information is very well organized and presented in a very intuitive user friendly format. Plus, battery life on the ipad is around 8hrs with heavy use.
I would also say that in addition to using foreflight on the iPad, I will print up approach plates as a backup for the iPad. While the upfront cost is higher than a years worth of charts, it pays for itself in more than just the cost of the charts but also in ease of use. I would recommend the iPad to anyone.