i enjoy the idea of conceptual themes rather than more strict, visual themes. the visual themes are good for photography class, but for juried photography exhibits and contests, and even for (IMHO) a deeper exploration of the subject, a conceptual theme would better serve.
what about love?
a theme of tranquility, depression, revolution, unity, discovery, healing, or power might stir up even MORE creative thinking.
my 2 cents. (again, from the kid who went to art school to study photography. granted, my cameras are all dusty and lonely and i hope this club helps me open back up again! digital just doesnt do it for me. gotta get the motivation to develop film again!)