Zotero Support Documentation:
These screencast tutorials provide a nice overview of Zotero, courtesy of zotero.org
Zotero [zoh-TAIR-oh] is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources. Designed to be intuitive and unobtrusive, Zotero is a powerful and handy tool for any academic.
Zotero is the only research tool that automatically senses content in your web browser, allowing you to add it to your personal library with a single click. Whether you're searching for a preprint on arXiv.org, a journal article from JSTOR, a news story from the New York Times, or a book from your university library catalog, Zotero has you covered with support for thousands of sites.
Zotero works on all three major operating systems: PC, Mac, and Linux.
Zotero collects all your research in a single, searchable interface. You can add PDFs, images, audio and video files, snapshots of web pages, and really anything else. Zotero automatically indexes the full-text content of your library, enabling you to find exactly what you're looking for with just a few keystrokes.
Cite perfectly - Whether you need to create footnotes, endnotes, in-text citations, or bibliographies, Zotero will do all the dirty work for you, leaving you free to focus on your writing. Create citations in Word and OpenOffice without ever leaving your word processor and add references to an email, a Google Doc, or some other editor simply by dragging one or more references out of Zotero.
Say goodbye to folders - Zotero organizes your research into collections that act like iTunes playlists. Research items can be added to any number of named collections and subcollections, which in turn can be organized however you like. With saved searches, you can create smart collections that automatically fill with relevant materials as you add them to your library.