CiteULike, create your own library
CiteULike is a free service to help academics to share, store, and organise the academic papers they are reading. You can register free in a few seconds, and add the bibliographic information of the articles you read or found in some databases like ScienceDirect to your library, tag them with your keywords, write a comment or description about them. You can create or join a subject group and share the articles that interest you with others. You can monitor what other people or groups add to their libraries, which indicate their interest in articles (without invading their privacy). You can export the bibliographic information of the articles to Endnote. Also this service let you know which articles are more interesting as you see more people add them to their libraries.