Welie is a site that provides examples of design patterns. It includes web design patterns, handily categorised into (among others) types of sites, types of interactions, navigation, search and user experience. Very useful if you are stuck for inspiration. And as we all know, there's no point in reinventing something that's already been done before. And there's also the minor point of usability - when users become used to something it becomes a defacto standard. (Is that enough reasons to go and take a look?)
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