Citation Managers For Unix?

A studious Anonymous Coward asks: "So, I now mostly converted to Linux, however one key applications that is missing: a tool like 'EndNote' or 'Reference Manager', which is invaluable for collecting and managing bibilgraphic resources when doing scientific research and writting scientific papers. These packages will do things like maintain a searchable database of your references which you can populate off of one of the public citation databases (pubmed, etc.). Additionally, it interoperates with Word to format your bibliography and (re)number your references. Is there anything like this for Unix?"