that's all i've ever found when all three are together; it's bakushipping(a full-on threesome) or 2 are brothers and one's hooking the other up with the third. (with a few rare exceptions!)
i'd love to see a fic where 2 of the three are fighting/vying over the other one, i.e. Akeifa and Bakura are both after Ryou... so gem and tendershipping.
or one's trying to seduce another away, i.e. Bakura's trying to steal Akeifa from Ryou... gemini and gem shipping.
whichever way you wanna do it, whoever's paired together, as long as it's not bakushipping and they are not related in any way!
oh, and if there are already some out there i'd love a link!