I've thought about ammonia as a life solvent--it's not quite as polar as water so it's a better solvent for aliphatic organics. I also remember a cartoon in OMNI from the 70's that pictured an alien crawling across a desert captioned with ammonia, ammonia.
Even more interesting is just to consider other binary possibilities. Silicon instead of carbon, plasma flops---
The discovery of non human intelligence is going to become ever more important---after all we are just beginning to recognize non-human intelligence on this planet.
We are, after all, just an amazingly arrogant moderately intelligent monkey.