
BEAVERS:


Irrigation techniques, dams (obviously), protective moats, amphibious habitat construction, hydrodynamics, use of a snow roof as an insulator.

Terraforming techniques. Beaver dams, and the ponds they create, have an immense potential to change the entire surrounding ecosystem, usually for the better. The wood that is chosen naturally by the beaver will more often than not truncheon (sprout) and form roots and trees that further enforce the dam and eventually form a permanent nigh-immovable part of the landscape. River salmon runs depend heavily on beaver ponds for their breeding pools. Rich farmland is created at the bottom of the ponds while at the same time excess nutrients and toxins are removed in the process. Denitrification helps recapture excess nitrogen in the atmosphere. Diverse biosystems for songbirds, frogs, toads, etc, are given a literal oasis of shelter, food, and water. Beavers have not only figured out how to terraform the land, often to nature's benefit, but do so without mechanized earth-movers, nanomolecular robots, or union labor. They do it with on-site materials, often overnight, and must live within the results of their labor.
CADDISFLY LARVAE:


Composite materials construction, camouflage, and mobile homes, use of the home as a method of obtaining food.

The same combination of the four that the caddisfly larva manages to achieve. Imagine the possibilities of a mobile infantry or even a planetary exploration vehicle that also serves as a home that can be easily crafted or repaired compositely from any local materials, is capable of being expanded upon when demand calls for it, is perfectly camouflaged, is mobile, and can be used to obtain food.
ORB-WEB SPIDERS:


Suspension bridge construction, the strength of the Y and the arch, polymerization.

Advanced lightweight materials fabrication techniques. Certainly knowing how to make spider silk would be cool, but what would be even better is fully understanding the "how" of their formation, and how we can apply that knowledge to the creation of other, even more incredible materials. The advent of nanotechnology will almost certainly lead to this in time, and has already resulted in carbon nanotubes, which show amazing potential.
SOCIAL SPARROW WEAVER:


Apartment quarters, cooperative living with other species, long-term urban planning.

More communal architectural techniques. Our basic apartment complex has changed little in the last few thousand years, and those who had different or unique ideas were quickly lost to the extremely overused and "blocks and courtyards" method of dense residential housing. The need for privacy, combined with the need for efficiency of space, is a battle that is continuously being fought between architects and developers. Profit typically wins in the end, though quality of living at a lower cost should be the true litmus test of a good "apartment". If we could figure out how to get an apartment complex to have the same sense of community as a suburban neighborhood, with the energy and space efficiency of a high-rise, the capability of housing guests, and an energy efficiency that far outstrips the cheap construction methods used for most apartments, then humanity will have made the next--and arguably most necessary--leap forward in housing.
HONEY BEES:


Extremely low-budget housing construction. In some countries, the honeycomb shape is used to stack more coin-op "coffin beds" (think of a hotel room the size of a coffin), and in Slovenia there is already a low-budget housing project based off the honeycomb shape.

More uses for the honeycomb structure. Honeycomb architecture is being actively researched. Engineers, architects, and designers are scrambling to fully realize the modern possibilities of this shape, from the nano-molecular to the macro mega-structural scale.
ANTS:


Hallways, traffic control measures, production lines, specialization.

Emergence theory. Swerve theory. Collective intelligence. Hive minds. These are already being investigated, but not yet fully understood, but it appears to happen all over nature, and even amongst cities. The idea is that if every organism's direction is purely randomly based, that eventually one organism will experience a positive event at a specific location, as opposed to a negative event or a non-event elsewhere. This positive event will then be experienced by another organism, and another, and another, while the other non-event and negative-event locations experience less traffic. The result is that a major thorofare develops between "home" and the "positive event". Similarly, the collective average guess of a crowd will--the vast majority of the time--be more accurate than the guess of any one individual in the crowd. Contrary to all popular belief, the larger the crowd, the more intelligent it appears to become, on average, on accident. The ability to apply detailed knowledge of this to architecture, urban planning, and traffic would allow for a complete revolution in the way cities are designed, how landscaping is handled, and how all are connected to one another.
CONCLUSION:
If we can somehow manage to learn even a fraction of what nature has left to teach us, we can expand the horizons of habitability to new levels. As human population levels continue to increase and the Earth approaches the nigh-inevitable 10 billion count, we can no longer rely on tradition, aesthetics, and the assumption that only the future holds the solution. In many cases, the solutions to housing the world are all around us, we merely need to stop long enough to discover and appreciate them.