Astrobiologist Chris McKay of NASA's Ames Research Center has hypothesized the presence of a "cryolife" in Titan. The organisms would breath hydrogen instead of oxygen, use acetylene in place of glucose, and exhale methane. This scenario could certainly explain some of Titans odd chemistry.
Titan may also have an ammonia-water subsurface ocean. Ammonia could be as gentle to organic molecules at least as well as water is.
McKay has considered the feasibility of methane habitable zones around the most common stars in our galaxy, red dwarfs. These stars are much cooler than the sun and so the habitable zones could be as close to their stars as Earth is our sun, or even closer.
If Titan orbited a red dwarf, more light for powering life would reach the surface because Titan's atmospheric haze is more transparent to infrared light.
McKay thinks there could be many Titan-like worlds beyond our solar system that have surface methane lakes and oceans.
Therefore, the whole idea of just one type of habitable zone in the galaxy may be terribly geocentric thinking. On the other hand, could intelligent life arise from other exotic biochemistries?
At cryogenic temperatures the metabolism of such creatures would pass at a glacial rate. So their life activities would be very stretched out relative to ours. A conscious entity's perception of time's passage would be markedly different from ours.
Nevertheless, such beings might regard water-worlds as unlikely places for finding evidence of life, just as we would regard a world covered in molten lava. To them we would live in an uninhabitable zone.
Images courtesy ESA and NASA