The University at Albany libraries have a very comprehensive citation guide in beta, CitationFox, for MLA and APA citation styles. You have to identify what type of material you have in front of you, and it then gives examples of citing that type of material, and any additional tips. They welcome feedback. On the US discussion lists ili the main issue raised has been that students may not easily identify what type of material they have (e.g. whether it is a journal or magazine article), but it would be useful for students (or indeed academics) past that stage, because of its comprehensive nature and the number of examples. http://library.albany.edu/usered/cite/
Photo by Sheila Webber: A bullfinch, I think, in Tallinn, May 2011.