Whizbang Dustyboots
Gnometown Hero
This is my answer as well, although substitute "everything in Monte Cook's The Year's Best D20 book made me consider buying the original products" instead.I normally would have said zero, but Mouseguard running the board last year (I think?) certainly made me consider it.
So it depends on the award. But everything in YBD20 was so good -- even if I have no call to ever use the Yogi 3E class, for instance -- that it definitely put products, publishers and creators on my radar who might never have been there otherwise.