Zone Of Curiosity.
Buried within one of the links from Faris's post about a viral movie marketing campaign (trailer highly recommended), I came across this graphic which seems to fit well with this week's first two posts.
If what you do is neither noteworthy nor mysterious nor not so different from the norm you'll elicit disinterest. If you get over-complicated or particularly geeky, you won't see the eyes glazing over but they will. However, if you edge people just beyond their comfort zone, make it a little challenging for them, then you'll risk engaging them. Give it a try.
Addendum: For those of you who want to counter with the infinite segmentation/personalisation argument that's all very well but it does have consequences.