Morphological Anti-Aliasing.
One of those innovations which only in conjunction with half a dozen others, all similarly hogging your system, will impact the visual settings significantly. Do not misunderstand me though, here one must appreciate the significance of significantly on one's own, there are keen eyed graphic junkies out there for whom the individual feature is a deal-breaker I am sure.
Should you find yourself inclined (the image presented in the header is one of the best yet rare examples where MLAA impacts heavily):
http://visual-computing.intel-resear.../mlaa/mlaa.pdf
Bookmarks