...gift-giving (Mauss, 1925): Giving gifts creates an obligation to reciprocate, tying people together in bonds of mutual obligation.
...collective effervescence (Durkheim, 1912): People engaging in repeated ritual action which aligns their focus on a common object (Erving Goffman called this "interaction ritual") and who become attuned to one another have a shared intense experience that generates what Randall Collins calls "emotional energy."
...symbolic violence (Bourdieu, 1970): Interests of different groups in society run counter to one another, but the dominant classes and their elites manage to universalize their interests by inculcating subservient dispositions among the dominated through education and other cultural institutions.
A few more that I don't care to elaborate right now: kinship (Levi-Strauss, 1949), libido/cathexis (Freud, 1899), orgone (Reich, 1940), imagination (Castoriadis, 1975), interdependence (Elias, 1937).