I suppose that any 3D editor capable to import fbx can be used - 3ds max, blender (this is free) etc. But many times is preferably to create an empty object and child your model to it - this way you can rotate the model to the correct orientation, and also move it so that the pivot (empty object position) is where you want it to be - Unity gives some hints about this in http://unity3d.com/support/documentation/Manual/HOWTO-FixZAxisIsUp.html