Termites are very common; they build huge nests. The nest is frequently twice as deep as the pile is high and some mounds were about 8 feet high. Termites are apparently very efficient in that they eat and re-eat everything several times to extract all nutritional aspects of their food and then use the remainder to construct their nest.
There are also many Weaver birds who make quite handsome nests on trees. Sometimes you see a tree with 30 - 50 nests.
And then here is one form of house from one of the many Tanzanian tribes.