they haven't met much because of 2 reasons:
Nadal on fast surface dont reach later rounds that much to face rodick.
Rodick on slow surface dont reach later rouns that much to face nadal.
it's a bit funny that they don't seem to make it to the latter stages of the same tournament together too often. generally if one of them is in a quarter or semi, the other has already lost in a previous round, as if they're almost never in form at the same time. i'd like to see a late-round match at wimbledon between these two, as they've combined for the other spot in the final since 2004 without having to go through one another.