More control of the curves in the animation palette.  Other 3D programs give this option, like the pen-tool in Photoshop, there are two handles on each side of the keyframe and you can pull each handle to adjust the way the curve goes from the previous keyframe to the current keyframe to the next keyframe, and so on.

Fine control over the interpolation!  I needs it, precious!  :)

(See attached image to see what I mean.  From Blender.)