With citation management tools, you can store and organize citations downloaded directly from the online library catalog and most Library databases.  The The History, Philosophy, and Newspaper Library recommends Zotero.  

Free. Works with the Firefox 2.0 web browser. Developed by historians to support historical research. Flexible software allows you to take snapshots of web pages, and to organize your notes along with your sources. Is not web-based, meaning that you can get access to your files only on your own PC, whether or not you are online.   Zotero software and all of the files are located on your hard drive. A special plug-in allows you to insert formatted footnotes and bibliographies into MS Word.

EndNote is also a popular citation management tool. Users of EndNote currently must purchase the software.