OGLE-2003-BLG-235L System - A red dwarf around which the first planet discovered through microlensing was detected in 2004, shattering planetary distance records. It took a few years to actually image the star itself (by Hubble).
OGLE-2005-BLG-169L System - Contains the second discovered icy Super-Earth or Neptunian. This planet was detected via the Microlense technique.
OGLE-2005-BLG-390L System - Has first discovered Icy Super Earth, which was detected via Micro-lensing tens of thousands of light years away and was the smallest known exoplanet around a normal star at the time.
OGLE-2006-BLG-109L System - The first multi-planet system discovered via microlensing. Contains a Jupiter and Saturn analog, the first such system discovered in positions predicted by classical theories of solar system formation.