[R] Heat Maps

[Jacques Wagnor]

Dear List,

Does there exist a function that produces a heat map like this one
(image 3 of 4):

http://www.tdameritrade.com/tradingtools/options360.html?a=HDY&referrer=http%3A%2F%2Fquery.nytimes.com%2Fsearch%2Fsitesearch%3Fquery%3Dheatmaptype%3Dnyt

In addition to colors, two other main features I am intersted in are:

1. Proportionality in the size of the grid.
2. Mose-over capability.

I may have missed it, but I've had a look at heatmap() and other
similar functions, but to no avail.

Any help or pointers would be greatly appreciated.

Regards,

Jacques