  The near-horizon geometries of the extremal Kerr black hole and certain
generalizations thereof are considered. Their isometry groups are all given by
SL(2,R) x U(1). The usual boundary conditions of the Kerr/CFT correspondence
enhance the U(1) isometry to a Virasoro algebra. Various alternatives to these
boundary conditions are explored. Partial classifications are provided of the
boundary conditions enhancing the SL(2,R) isometries or separately the U(1)
isometry to a Virasoro algebra. In the case of SL(2,R)-enhancing boundary
conditions of a near-horizon geometry of the type considered, the conserved
charges associated to the generators of the asymptotic Virasoro symmetry form a
centreless Virasoro algebra.
