Zotero is a free tool that you can use to collect, organize, cite and share resource sources. You simply set it up and then click the "Save to Zotero" icon in your Firefox web browser. Chrome and Safari plug-ins are in Beta now.
There are also plug-ins for Word and OpenOffice that allow you to citations and bibliographies directly into your document.
Zotero stores all of your research in a searchable interface, supporting PDF's, audio and video, images, web page snap shots and more.
There is a Groups function for sharing and collaborating, forums, documentation, and a list of users by topics.
If you use it with a lot of research and data, you can upgrade your storage for a fee.