Open Source Citation Editing Tool
Over the past year Mendeley has collaborated with Columbia University Libraries on a project funded by the Alfred P. Sloan Foundation to create a new open source CSL Editor. It's the first true 'what-you-see-is-what-you-get' (WYSIWYG) citation style editor for open source CSL citation styles. This open source tool is now integrated into the latest release of Mendeley Desktop. The code for the CSL Editor is available under the MIT license.
Read more about it on the Mendeley Blog: http://blog.mendeley.com/academic-features/make-your-citations-look-exactly-how-they-should-with-mendeleys-visual-citation-style-editor/