My apologies for not being online yesterday. I went out of state and wasn't back until after midnight. Now then, I would like to answer your questions with demonstrations:

The Sonic head to the left is shaded normally for that style, however, the Sonic head to the right is not. This is a shading technique referred to commonly as pillow shading. Seth's explanation was very much correct. It is when the spritist in question is using a darker shade of the same color inside the border of the sprite, and then keeps using lighter colors to trace the next border until the space is full. For newer spriters it does give off a nice effect indeed, however, it's not an effect to be imparticularley proud of. When ever you use these pillow shaded sprites in comics, flashes, or otherwise they end up looking off and they just give a less than professional look. I'd like all who read this to try to stay away from this type of shading and try shading by using a "source of light" in order to determine where the darker and lighter shades of said color should go. I don't always use this method because I often work with what I would like to call "Pitch Dark" shading technique, in which I shade it all dark toned in order to bring out the effect that said character is either in total darkness or dimmed light setting. I do this for the sake of what I might use the sprites for, though. Recently I have been adapting to Seth's style for the reason that we are both working on a certain project.
Now then; you wish to improve your recolors? I must first know what you do to recolor said sprites. Do you do it all by a brush or what?
Now to answer the final question: Inspiration is different for each person, but I can tell you ways I usually get inspired to do something. I usually get inspired to think of story ideas while I'm listening to music of a certain genre that would suit said story or scene. Strolling through Deviant Art would inspire me to draw more. (Though it doesn't last long) My inspiration for spriting is looking through official sprites and trying to adapt to many kinds of techniques in order to find one that suits me the best. Again, it's different for everyone. Basically if you want to get inspired, look through the work of experts.
And yes, BlackAngel, I was just throwing that out in the open. I'm sure all will be just fine indeed.
I'll be back to answer questions at around 11:00 P.M. (Eastern Time)