See, LarryNiven and JerryPournelle wrote this really fun book called ''The Mote in God's Eye''.  It has a cool title, some questionable biology, and a huge debt to RobertHeinlein.  It also gave us "on the gripping hand", one of speculative fiction's more useful phrases.

In this case, the aliens of the series are an asymmetrical sepcies with three arms, one of them geared to heavy-duty gripping tasks.  The characters extend the "On one hand" and "on the other hand" phraseology when there's a third possibility that contrasts with the first two - and generally overpowers or renders them irrelevant.

Example:

* On one hand, JohnWilliams composes great movie scores.  I love them.
* On the other hand, John Williams' scores often sound similar, and since he's so popular, he's used in a lot of movies, which contributes to a common musical style for Western movies.
* On the gripping hand, maybe this is all personal preference anyway.