NaviLights is an overview application for the iPhone, that helps you identify navigation lights at night at sea.
In the "Night" section you'll se a table of different light configurations as they would look like seen from starboard, aft, port or front. This table is divided into sections like "Power driven vessels", "Towing and pushing" and so on. All these sections are headed by a rule page describing the rule that apply as in the "Collision regulations".
The "Day" section is similar to the "Night" section described above, but here it's the shapes used in the daytime that are shown.