From D&G's A Thousand Plateaus [thanks Theo] so far, I've been most taken with the concepts of territorialization and deterritorialization. I've talked before about push and pull - from queue theory - as alternative ways of exploring a landscape. With pull, the landscape tugs at each step -- progress is blind, as with evolution. Push is goal-directed. D&G take a different cut across this and focus on two opposed dynamics. That is, a blend of push+pull has two different local outcomes (by local, I mean not just the portion that is exploring, but its whole area). These are territorialization (which maps fairly neatly to adaptation, in the simplest case) and deterritorialization, which I find way more interesting.
Exaptation, "from, so to speak, one aptness to another", is: the feathers of birds previously used for retaining heat being turned to flight. Or, (the example in ATP), humanity's move to the steppe allowing the larynx - that once had to be large to make noises to be heard in the forest - to be used for more subtle purposes, like speech. This is deterritorialization (and reterritorialization). It's an object becoming part of the landscape, something being taken for granted, the following iteration of a pull step where feathers also become secondary sexual characteristics, items in myth, duvet filling, figures of speech, quills. Or it's when (in Kuhn) a rogue scientific structure gets internalised and becomes the paradigm.
(Of course, I may have this all wrong. But who cares. ATP is fun(ny). It's laugh-out-loud witty in places. And it's really nice to have things sketched in my head so I don't realise they're appearing until they're there. Even if they are the wrong shape.)