You'd think that with John H. Conway around, this should be like shooting fish in a barrel. One title that comes to mind is * The Sensual (Quadratic) Form and there are more goodies if you look at his <a href="http://www.math.princeton.edu/WebCV/ConwayBIB.pdf">bibliography</a>. For example, * Character Calisthenics or * $\text{The} \ \sqrt{\text{Monster Construction}}$ I also like the paper (both the title and the contents!) by Andreas Blass, * <a href="http://arxiv.org/abs/math/9405205">Seven Trees in One</a>