The free...

Nikon Learn & Explorer 1.0 (iTunes App Store)

...iPhone app is a clever piece of pre- and post-sales marketing for Nikon's Digital SLR (Single Reflex Lens) camera products. It helps DSLR owners learn to use their high-end camera better by providing descriptions of techniques along with photos and videos to illustrate those techniques. It also provides a photography glossary to explain various photographic terms. The information is quite useful and educational. The photos are stunning. However, the load time for the photos is quite long over a WiFi connection. And, the one video I tried to view stalled after a few seconds of streaming and buffering.

However, the price is right (free). And, the photos are amazing to look at and worth the long wait needed to download them over the network.

Via CNET: Nikon app teaches photography on the fly