RefWorks is a Web-based citation manager that allows you to import references from text files, web sites or online databases. You can use RefWorks to format a paper and a bibliography in seconds. (First time users should sign up for an individual account and select a username and password).
Here is a brief guide to walk you through the process to set up your account and other features of RefWorks.
Mendeley is free online reference citation management tool that allows you to manage, organize, write, cite and collaborate with folks locally and internationally. As a web-based tool, you can sync desktop and web searching.