Using Safari Xtra you will control your bookmarks from the main toolbar. Additionally you will can manage your cookies, search with the most popular web search engines (Google.com, Alta Vista and many others...), cleaning Safari archives (Downloads History, Cookies, Bookmarks, Cache...).
SafariXtra is fully integrated with the recents MacOS X technologies as like AddressBook: you can search for people directly from this software without opening the other progams.