dexpot is free (though not open source) and very customizable. It has a few idiosyncracies (e.g. can't drag a window by a title bar to a different desktop), but even with them, it's better than the many other solutions I've tried.
The addon Mr. Tech Toolkit has this option. Under its options Misc -> XPI install options -> Enable Addons Compatibility checking
It's not another link to the original site, but in the NYT recently Errol Morris was researching an unrelated Civil War story, and one of the sources was David H. Kelly, who did major work deciphering the Mayan script. In passing Errol asked about the 2012 thing: http://morris.blogs.nytimes.com/2009/04/01/whose-father-was-he-part-four/
area. the mass is minimal. from a bbc article "Indeed, so feeble is the ring that scientists have calculated that if all the material were gathered up, it would fill a crater on Phoebe no more than a kilometre across."
http://news.bbc.co.uk/2/hi/science/nature/8291905.stm
To help with the window management required to do this (and if you run windows), look into the freeware app Gridmove. You can divide up your screen real estate into many different chunks, and have all sorts of handy ways of resizing your windows.
But the upgraded/final release came out just now and Penny Arcade covered that as well (just 6 days ago).
http://www.penny-arcade.com/2009/1/9/
http://www.penny-arcade.com/comic/2009/1/9/
also you find what a rhombus is.
Anyone can make an omelet with eggs. The trick is to make one with none.