Project Extension Page: https://chrome.google.com/webstore/detail/fjiolbglibkahkipcdgeepdfdgfkdbee?hl=en-US
Some source code derived from http://code.google.com/p/music-beta-controller/
Apache License 2.0
Implemented by Kyle Kamperschroer

antimatter15's notes:

relayouted interface based on a few principles:
1. Fitts's law: The interactive elements of the popup have been moved to the top to minimize user activity
2. The buttons have a semi-interesting layout idea. The left is populated by "positive" actions and the right by "negative" ones.

The first one is relatively self explanatory, if the user is going to click the button, he or she probably intends on interacting, and minimizing the amount of time used to move the cursor optimizes user efficiency. Sure, it's minute, but it's the details that makes a usable interface.

The second one is more interesting, or at least to me. There's a sort of symmetry to the design across the middle, there's previous which is the logical opposite of skip/next on the opposing side. Then lies thumbs up, whose obvious foil is thumbs down. Then is repeat, the somewhat less clear opposite of shuffle (Repeat indicates the user's desire for more attention toward a song, whereas shuffle represents a certain degree of apathy in which the user doesn't particularly care which song is played next).

The items to the left of the play/pause button, which lies in the center and represents neutrality, represent "positive" actions. By that, it means that it means positive afflictions with the song, however abstract. Repeat represents the strongest feelings toward a particular song, that the user intends to hear it over and over again until it's drilled into their very existence. Next is thumbs up, which represents the user's liking of a certain song, and finally is back, which indicates the user's intention to hear that last song one more time.

The "negative" actions are skip, thumbs down and shuffle. Skip indicates a temporary disliking of the song, maybe he and/or she has heard it too many times that day, but doesn't necessarily hate it. Thumbs down indicates that the user not only doesn't like it at a certain point in time, but doesn't want to hear it in the future, it's clearly more intense than skip. Shuffle doesn't follow the pattern of intensity spectrum, but it's still a "negative" action, as it represents the idea that the user doesn't particularly care about the identity next song, and feels that the structure of the playlist (which generally has some structure, as intended by the artist) doesn't fit his/her desires and would like serendipity to take over instead. 

I guess that concludes my overanalysis of some little idea.