Zotero is both a Firefox add-on and a desktop application (you can use it if you don't use Firefox as your browser) that saves citation information AND saves the source doc to your computer if you'd like to use the source again or access it offline.
It works well with the South digital library, with one-click additions to your database. It also allows tagging to organize references. It also does limit formatting for your cites and bibliographies.
For those of you that plan on doing more research, it is a great tool.