The new BBC homepage does something amazingly clever. Matt Jones sums it up:
Go there… click on News or Sport then click back to the homepage. Try doing that a few times… Notice the background colour of box which you clicked the link from gets a few shades different?
It’s all coded so that whatever you click most gets reinforced over time, making it easier to find what you always want. A gentle, reactive form of personalisation that doesn’t take away any choices
(via Blackbelt Jones)