First, the official Nike website.
The website has a very focused sports motif. The background behind the main content is the turf on a football pitch, with the white painted lines. This sets the tone for the rest of the websites photographic style. All of the photos in the navigation at the bottom are in the context of sports (e.g. Wayne Rooney kicking a football). The range of Nike shoes displayed on the front page also seem to be designed to appeal to sports fashion.
The visual style for the website is a very clean and sharp interface, with soft rounded corners and high contrast text. It uses a lot of bright colours with dark text. It uses solid blocks of white and orange which looks very clean and simple. Along with the photographic visuals they work together to convey a glamorous or smart and appealing image of sports rather than a more realistic depiction with the dirt and mess associated with playing sports. Nike is clearly trying to set an image of high quality and cleanliness in their brand.
Nike's other advertising and branding seems to be split two different styles. First is the most direct advertising, usually in magazines where it is a photographic image of the shoe. The shoe is the main focus of the image usually, put in an abstract image or in the context of sports. Here are some examples:
The other type of advertising seems to be less focused on the product, more on the brand. This happens in their TV advertisements where they have video of general sporting activities, or inspirational messaging over sports to create an air of inspiration, achievement and excellence around the brand. For example, this Nike ad:
The term 'My Better is Better' refers to sporting ability and achievements, set to slow motion footage of sports men and women performing feats of agility, strength etc. Very little Nike products are actually shown, it is only subtly shown to the viewer through the clothing the people are wearing. The message promotes excellence, and the implication is that the brand, Nike, is associated with the message and the concept of excellence in the context of sports. The logos is shown at he end with the main slogan "Just do it.", which in itself is an inspirational message.
There are others, such as this humorous ad featuring Roger Federer, but again it is a representation of sports, in this case a strange comedy 'sketch' featuring sports, and the brand added on to the end in an abstract association. It isn't pushing a product on the viewer, it's associating the brand with a concept or 'feeling'.
There are exceptions to these advertisements but the main amount of advertising that I was able to find followed this pattern with their own variations.