Louvre HD (US$1.99) is a beautifully done app that takes you on a virtual tour of one of the greatest collections of paintings in the world.
The app provides access to 2,300 paintings from the Louvre in Paris that can be viewed in very high resolution. Louvre HD itself isn't that large (only 76 MB), but requires an internet connection to access the high-resolution images of the paintings.
The works are organized by century and cover 800 different artists. There is a quick search function, and paintings can be saved to your iDevice or mailed to friends. The high-resolution images invite exploration, because you can two-finger zoom and really explore these painting in great detail.
Louvre HD also has a slideshow mode with adjustable speed, and you can even choose some classical music to listen to in the background.
I think the only thing Louvre HD lacks is any detailed information on the paintings or the artists. Links to Wikipedia or other sources would be most welcome. Still, it's hard to argue with the quality of images of the paintings. I spent a lot of time examining and enjoying the paintings I explored.
There is a free version of the app with only 400 paintings, and it will give you a taste of how the app works. The free version has an in-app purchase feature that allows you to upgrade to the full app. If you are actually visiting the Musée de Louvre, there is a nice free visitors guide app that will help you navigate the huge museum.
Louvre HD is a universal app. I thought it would have the most impact on my iPad, so that is where I reviewed it. iOS 5.0 or later is the minimum requirement, and the app is optimized for the iPhone 5 screen.