Tolkien and Philosophy

While looking for sources for our multimedia research project I found a book called The Hobbit and Philosophy: For When You've Lost Your Dwarves, Your Wizard, and Your Way. I haven't actually read it but I know that several people in class are actually philosophy majors or are very interested in the topic. So if you if you want to connect Tolkien to philosophy this looks like a good source. Also, just googling Tolkien and philosophy comes up with a whole bunch of different books if you need more sources or references.
For Discussion: what are some of the ways you would connect Tolkien to philosophy? or what are the subjects you are interested in for the research project?