If you haven't already read them, then "In Search of Schrodinger's Cat" John Gribbin) and "Fermat's Last Theorom" (Simon Singh) are quite readable introductions to some arcane theories. I've got another maths book here called "Why Do Busses Come in Threes" but I haven't read that yet - I'll move it up Mount TBR and review it for you :o)

One of the reasons I did science at School/Uni was that I knew I could pick up arts/humanities much more easily when I was older, whereas there is a real dearth of stuff regarding maths and science for the returning learner/enthusiastic amateur. I've not seen anything since to disprove my adolescent theory :o/