I got this idea from SpaceKnight of Chaos's "What couples do you like?" thread.
So here is my list
RanmaxLum (Urusei Yatsura)
RanmaxHikaru (Magic Knight Rayearth)[My favorite]
RanmaxA-ko [My second favorite]
RanmaxYoko (Devil Hunter Yoko)
RanmaxSailor Jupiter
RanmaxSailor Venus
RanmaxSculd (Ah My Goddess)
RanmaxBirdy (Birdy the Mighty)
RanmaxAyeka
RanmaxKiyone
RanmaxNukuNuku
All of my other couples are Ranma/Urusei Yatsura parings
UkyoxTobimaro
ShampooxRei
MoussexOyuki