What exactly is a mood board?Mood boards (sometimes called inspiration boards) are used in a variety of disciplines. You’ve no doubt seen them used for Interior Design, where fabric swatches and paint chip samples are grouped together on a poster to show a homeowner what type of atmosphere the new decor will create. They are also used frequently in Fashion to highlight trends and styles. In essence they are a compilation of inspirational elements used by designers to flesh out ideas at the beginning of a design project.
A mood board is extremely useful for establishing the aesthetic feel of a web site. It usually fits into the process somewhere after wireframes and before design mockups. Things that can be explored in the mood board include photography style, color palettes, typography, patterns, and the overall look and feel of the site. Soft or hard? Grungy or clean? Dark or light? A rough collage of colors, textures and pictures is all it takes to evoke a specific style or feeling.
The mood board is intentionally casual; it lets the designer start with broad strokes and get feedback before too much time is invested in the wrong direction. Think of it as rapid visual prototyping.
Text from : http://www.webdesignerdepot.com/2008/12/why-mood-boards-matter/