IIRC, expanding with programming languages (PLDI, CGO, ISMM, OOPSLA, etc.) was already discussed when this link was first mentioned on HN. Unfortunately, it seems to not have been done yet...
Anyways, PLDI has the "Best of PLDI" papers from 1979 to 1999 (http://www.informatik.uni-trier.de/~ley/db/conf/pldi/pldi200...) and they establish the most important paper 10 after its publication. AFAIK/IIRC OOPSLA/SPLASH does this now as well. I think it's good, but it would also be very interesting to know, whether there is an intersection between the set of "Best Paper" awards and the set of "Most important/impact" awards.