Meet Itching Thumb, an absolutely amazing task switcher that's very similar to the one found on WebOS. There's not much I can say that rivals what's shown in the video:
For those who are unable to watch the video or who are unfamiliar with WebOS, it's basically a "card" system - similar to CoverFlow (but with a customizable style). These screencaps illustrate what I'm talking about fairly well:
Left: the cards are flat as you scroll; you can drag an app to the top of the screen to close it (shown).