Zotero is available for free to everyone.
Zotero can either be embedded in your Firefox browser or downloaded and installed on your computer. Zotero is most useful for:
Collecting and organizing different types of references (Web pages, audio, video, etc.)
Create citation and capture snapshot of websites with a single click
Assign tags to references
Three options for creating groups
Inserting citations and creating bibliographies
Plugins allow you to insert citations and create bibliographies in word processing documents
Create indpendent bibliography for grant reports, CVs, etc.
Quick Copy feature allows you to drag and drop references into any text field (email, blog post)
Few output styles standard, but many available for download
Working on any computer
Syncing allows you to access your Zotero library from any computer with internet access