Right off the bat, it is titled perfectly. There are How-to articles, images for inspiration, glossary of terms and videos. I have peeked around a bit and like what I see. Even if you are not a Nikon shooter, it is a useful little app worth a look.
Secondly, if you are a Nikon shooter and your camera body is the 1.5x DX Sensor (D40, 60, 80, 90, 200, 300), you need the AF-S DX NIKKOR 35mm 1.8/G lens. This acts like a 50mm lens on the 1.5x sensor. It is super quick to focus, razor sharp all the way to 1.8 and the colors that come out of it are superb. The lens is $200.00, which is a steal if you ask me.