CW Samurai//Soulknife has pretty low synergy as well...and unless you name the class "Soul Fists" Soulknife//Monk is just a Monk with Wild Talent, Speed of Thought, and the ability to one shot a T-Rex at 13th level with Knife to the Soul.
I nominate Monk/Soulknife for worst gestalt class combination.
CW Samurai//Soulknife is not a weak combo ... and has very good synergy look at the example i posted already, as for
Monk//Soulknife, ...... this is not that bad ,you can use several feats to make it strong.... notice:
from here:
http://www.wizards.com/default.asp?x=dnd/ebds/20050110aFlowing Blade [General]
Your mind blade is an extension of your body and soul, and you wield it with the same grace as your foot or fist.
Prerequisite: Ability to generate a mind blade, Weapon Focus (mind blade), flurry of blows class feature.
Benefit: You can treat your mind blade as a special monk weapon so that you can perform a flurry of blows with it.
Special: A kalashtar or Inspired monk can select this as a bonus feat at 2nd or 6th level, in addition to the normal options available at those levels. They must still meet all prerequisites for the feat.
now you can Flurry with your Mindblade(2 handed) while Leap Attack and PA for lots of damage .... even throw a Flurry of Mindblades, combine with TWF tree, and you have lots of Thrown attacks(throwing +9 Bastard Swords around)
you can use Intuitive Attack and Zen Archery to be more single Attribute dependant...... Wis to Attack(Melee or Ranged), and to AC also you can pick Psionic Feats