Color for Page and Site Organization

Color can be very useful as a visual organizer either on a page or within the site structure. On the site level, designers often identify areas of a large site by color. They use the same top banner and navigation but change the color scheme. Site visitors know instantly where they are in the site. Is this technique effective in this web site example (click on a few navigation buttons and look for color changes)?
http://www.americansforthearts.org/

This example features several zoos that are color coded. Viewers know instantly which site they are looking at:
http://www.zoossa.com.au/home

Is color used as a good organizing element in this site?
http://www.photographymuseum.com/

On the page level, designers often use color to visually separate groups of information. This might take the form of lines, borders or even different colored boxes. What do you think of the use of color for content organization on this site?
http://www.updatelegal.com/default.asp

Color is also useful for visually organizing a schedule. Here are two examples:
http://www.nywaterway.com/
http://www.metrostlouis.org/

Try to apply these organizational techniques to your sites!