iPhotoTool provides the ability to import a selected series of folders into iPhoto 5 or 6, and can take advantage of the new iPhoto 6 'don't copy imported files' feature. It uses the folder names as album names - and also attempts to never import a duplicate file.
iPhotoTool also includes an 'orphan' finder to locate photos that are not referenced in any of the user-created albums.
RequirementsMac OS X 10.3 or later
*Previously available here