Here are some new, and not so new, encyclopedias that might be useful for students in UWP classes if they are having trouble coming up with a topic or need a brief discussion of a concept. Often the bibliographies can help locate some useful titles for very general subjects, as well.
General Encyclopedias
Encyclopedia of Philosophy
Butler Reference Desk R031 En2 and online via the Gale Virtual Reference Library
Besides general philosophical concepts, this is useful for the plagarism/influenct topics, especially the article on "Responsibility"; it is also helpful for animal rights, and the idea of nature.
Routledge Encyclopedia of Philosophy
Butler Reference Desk R031 R76 and online
Ditto for the above topics, but I have found that often the Routledge articles are a bit denser.
International Encyclopedia of the Social and Behavioral Sciences.
Butler Reference R033 In818 and online
Good, general entries, including one on "Nature, concepts of"
Specific Subjects
Encyclopedia of Aesthetics
Butler Reference R037.01 En19
Also available in Oxford Art Online (though there are no page numbers, so it is harder to cite than the print)
There is a very useful article on the aesthetics of photography, and also one on nature, the "Moral Rights of Art", as well as one on originality, very useful for "The Extacy of Influence".
Encyclopedia of Ethics
Butler Reference R031.17 En191
Has entries on "Plagiarism", "Copyright", and also on ethical issues relating to animals.
Encyclopedia of Bioethics
Butler Reference R031.7 En18
More animal rights, as well as ethics and nature.
Mythical and Fabulous Creatures
Butler Reference R398.4 M44
A collection of monsters.
Tobacco in History and Culture: An Encyclopedia
Butler Reference R033.941 T55
A tour of Cancerland.
Science, Religion, and Society: An Encyclopedia
Butler Reference R035 Sc27
Encyclopedia of Science, Technology, and Ethics
Butler Reference R036 En2
Encyclopedia of Environmental Ethics and Philosophy
Butler Reference R036 En1928
Encyclopedia of Death and the Human Experience
Butler Reference HQ1973.E544 2009
In case suicide is revived.
A Dictionary of Cultural and Critical Theory
Butler Reference HM621.D53 2010
A convenient collection of modern ideas.