Zotero: A free add-on for the Firefox, Netscape, and Flock web browsers. It's superb, and fully integrated into the browser, where most article searches are performed, and it can store PDF's or other files. It has additional free add-ons to link it to Microsoft Word and OpenOffice Write. For my personal use it far surpasses any alternative I have tried, including EndNote.
EndNote: A commonly used article/bibliography management program. Although widely supported, it's bulky, not terribly intuitive, and expensive unless you have access to it institutionally.
Nonmalignant Lesions in Breast Core Needle Biopsies: To Excise or Not to Excise? Jacobs et al. The American Journal of Surgical Pathology. 26(9):1095-1110, 2002.
