This is a report of joint works with Hiroshi Ohta and Mohan
Bhupal. The link of an isolated singularity carries a natural contact
structure. Ohta and I classified of symplectic fillings of the link, when
the singularity is either a simple singularity of dimension 2 (Kleinian
singularity) or a simple elliptic singularity. Based on it, Bhupal and I
studied the case that the singularity is a quotient surface singularity
and a rational determinantal singularity with reduced fundamental cycle.