The universal property is the property which contains /every/ tuple (x,y) in its extension, for x,y IN owl:Thing.
Carsten Lutz suggests adding the universal property to OWL 1.1, explaining that, among other things, it brings support for multiple anonymous individuals related in a tree-shaped way, and that it is supported in the underlying description logic SROIQ.
Micheal Schneider summarizes some of the discussion and introduces a way to create a universal property using current OWL 1.1 constructs.
let's assume we had an object property, owl:universal, that comes with the following restriction to its interpretation: it is symmetric, transitive (and thereby reflexive), and a super-property of all other properties (or those found in the ontology that owl:universal is used in)
we can use owl:universal to "simulate" (proper) existential quantification: e.g.
(someValuesFrom owl:universal C)
holds of an individual if somewhere in our interpretation domain, an instance of C exists. Similarly,
(allValuesFrom owl:universal C)
holds of an individual if all individuals are instances of C. For example, we could say that
(someValuesFrom owl:universal God) SubclassOf (allValuesFrom owl:universal SeenByGod)
to say that, if god exists, then she sees everything...
hence we can use this universal role to talk about elements "somewhere" in the universe/interpretation domain, and thus as an alternative to unnamed individuals.