Use logos judiciously. Aside from the logo for the site, use other logos only if your users know them well and you want to draw users' attention to them. Don't use a logo just because one exists for a particular product or program. For example, many government agencies design logos for each new initiative or program. Keep such logos for internal use — users don't need to see all of them. See the Coles image on this page for an example of how logos can clog up the interface.