Lately I have rediscovered Shadowrun 3rd ed. and am buying up the supplements as fast as I can read them. I have really been enjoying the backstory to the setting- and have been going through Corporate Download as fast as I can because it is fun reading. I have Dragons of the 6th World on my desk begging to be read- and Shadows of North America was a great purchase and read (and responsible for my renewed interest). The rules are a bit dense- but, uncharacteristically, I really dig the density of Shadowrun's rules.
I also have been delighted by the direction of the supplements for Feng Shui. Friends of the Dragon was a great book with lots of good crunch for my favorite system... Blowing up Hong Kong was a long awaited book that lived up to my expectations. Now, they have a monster book slated for release and I am pretty excited about that. I still have yet to buy Gorilla Warfare- but, man, oh man, I want it.
Anyone else? Any commercial products of lines really impressing you so far?