Secret Mission Axis and Allies
Pacific Dominance
For each turn that Japan controls all of the Pacific islands at the end of a full turn they are rewarded with a free transport or submarine to be placed at a factory of their choice at the start of their turn. (This would require Japanese control of Hawaii, Midway, Australia, and New Zealand.)
Germans in the Atlantic
Similar to the Sink the Convoys variant proposed by GWLlosa, if Germany has one or more non-transport naval vessels in the Atlantic Ocean at the end of a full turn, the UK must roll the die and surrender that many IPCs.