After my adventure with my phone I've got all excited about customising high tech things in low tech ways. And for ages I've been trying to make my Mac more useful for taking notes / to dos. The problem is, that whenever you remember something to do you have to switch it on, power it up, find the application, and then the moment's gone. And I can never find my notebook when I want it. So last night I attacked my mac with some blackboard paint, and this morning it's suddenly way more useful. I've gained a whole other display.
I guess you could do the same thing by just writing on it with whiteboard pens but that doesn't seem as interesting and there's something very satisfying about crossing off a to do by licking your finger and smearing it out.