There is a lot of spatial environmental and land use and cover data layers for analysis at national and regional scale. But you need to know where to find it. On-line data portals like the FAO geonetworks are making it increasingly easy to find the data. Yet, much data and data sources are dispersed over the Internet and one has to spend time to find the best data available.
I have started to keep links relevant to my work in a table to make it easier to find it back later. It is not complete by any standards, and for sure will never by. But I will try to update it whenever I find the time / feel the need. You can find the table on my Ecodiv.org website.