Ammonia as a Possible Solvent for Life

Ammonia (NH4), is abundant in the universe, and a strong candidate as a hypothetical alternative solvent to water.
At Earth-like pressures, ammonia is liquid only at extremely low temperatures, so hypothetical life using ammonia as a solvent might thrive in freezing (relative to water) temperatures.
Ammonia/water mixtures also have liquid temperature ranges (at normal pressures) well below that of just water.
Titan, moon of Saturn, is believed to have subsurface oceans of a liquid ammonia/water mixture.
Resources include: http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemisty

Fosdick's Astrobiology