Emphasize - Clarify
Keep on track - Add information
Support/reinforce - Simplify information
Graphics - use to support and enhance instruction
Site design - sets the mood and theme, enables the viewer to navigate through site, establishes an identity
Buttons - usually reflect the theme & enable viewers to navigate through site effectively. Can be images or text.
Bars - used to divide or separate information on page for clarity. Can be animated or static.
Charts - show trends, comparisons or relationships i.e. line, bar, maps, organizational charts.
Tables of data - often show trends or comparisons in numerical form.
Illustrations and images - use to show something difficult to describe, demonstrate a process, or depict an abstract concept.
Animation - use when motion or action will enhance, simplify, or clarify a concept.
Video/Sound - requires a fast modem and uses a large amount of Internet bandwidth. Use when motion is essential to communicate information:

Presentation of actual events
Historical reenactment
Compressed or expanded time
Dramatic representation
Simulation of hazardous events in a safe environment
High degree of realism

Sound - use to communicate something essential to hear
Music - to set a mood
Narration - to communicate a message