Manage and organize a paper's bibliography

I was looking for a good software to organize the bibliography of the papers I write. I found a good overview here: http://www.lib.berkeley.edu/BIOS/refman.html
Here are two softwares:

• Mendeley Desktop is a software that indexes and organizes PDF documents and research papers into apersonal digital bibliography.
  

• Zetero is a Firefox extension to manage and organize a research resources.