The National Academy of Sciences has released a report , entitled “The Limits of Organic Life in Planetary Systems”. From the Preface:
This report explores a limited set of hypothetical alternative chemistries of life by following a hierarchy of possibilities that have been ranked through experimental, exploratory, and theoretical work done in the past. The study briefly reviews current knowledge concerning the following questions or hypotheses and provides suggestions for future research.
1. What environments on Earth that are extremes by terran standards harbor life? How must life-detection strategies be altered to discover this life on Earth? What extreme environments have not received attention? Are there synthetic environments that better represent conditions on alien worlds?
2. What environments on Earth are so extreme that life with standard terran biochemistry has been unable to occupy it?
3. What life forms are possible, still based on carbon and still functioning in water, but with a fundamental difference in the method of reproduction?
The report can be downloaded free of charge as a PDF. See link below.
 Committee on the Limits of Organic Life in Planetary Systems, Committee on the Origins and Evolution of Life, National Research Council. 2007. The Limits of Organic Life in Planetary Systems. NAS National Academies Press. ISBN 0-309-10484-X. 116 pgs.