You need a barspoon. Plus, they look cool. Typically featuring a spiral handle (for easy twisting of the shaft) and a small spoon bowl with holes (for floating liquors), the barspoon is essential for stirring and layering drinks. It is also helpful when fishing cherries out of a jar.
Once you have used a barspoon you will never want to be without one when making drinks.
The mixing glass
The mixing glass resembles the glass part of a Boston shaker, but is normally wider and bigger. You use it, for instance, to stir a Vodkatini with lots of dry ice, before straining into cocktail glasses. The mixing glass can be replaced with any large, clean and tall glass vessel.