SharePoint Feature

Feature Concept
http://sharepoint.microsoft.com/blogs/mike/Lists/Posts/Post.aspx?ID=7

Working with Features
http://msdn.microsoft.com/en-us/library/ms460318.aspx

Extending SharePoint 2007
http://www.codeproject.com/KB/sharepoint/ExtendingSPS.aspx

Elements by Scope
http://msdn.microsoft.com/en-us/library/ms454835.aspx