Checking out Mongabay.com , I came across a very cool application of Google Earth to see the levels of deforestation across the world, including short data sheets per country. So you can quickly see that Malaysia has lost over 6% of its forest cover between 1990 and 2005 (according to different data sources), while China has increased its own by 25% over the same period of time.
The nicer discovery, though, were the other maps the same developer, David Tryse, has been creating on environmental issues (check them all out in his website ): the top 100 most Evolutionarily Distinct and Globally Endangered (EDGE) mammal and amphibian species, 34 biodiversity hotspots according to Conservation International, and protected area networks --or national parks-- worldwide, among others.
Note that the sources of data are rather varied. To view and explore the maps, you need to download Google Earth  and install it in your computer, save the KML file/s provided for each map (KML is a file format used to display geographic data), and open them from Google Earth. At the bottom of that list of maps, you will find a link to download all files at once if you want, and you can also subscribe to updates for new maps that David may come up with.