AddonChecker allows you to check pbo's or mission folders for addon-requirements. It is particularly useful for finding out whether missions need Combined Operations content but can also parse script files inside the pbo and tell you whether they are likely to use classes that will cause missing addon-errors at run-time.
It can also automatically add OA and A2 addons to the requirements for the mission, preventing players without both games being able to join.
Further details at the BIS forum thread:-
http://forums.bistudio.com/showthread.php?t=102271