A New Germ Theory [via ESR] about how many conditions (such as cancer, heart disease and even homosexuality) are infectous because, if they were genetic, they would be selected against so strongly as to disappear. Well worth the (quite long) read.
What I said this morning (it's just below this - read it first) is backwards. We don't need a way of marking sections as "this stuff is actually someplace else", we need inlink linking (like <img> tags put content inline). This is nothing new - Ted Nelson told us all this years ago.