In a post at Oprah.com, dietician Brian Wansink offers a series of hints on how to cut down on what you consume. Amongst them is this useful technique:
Drink from a skinny glass. Your mind perceives height more readily than width, so you'll think you had more.
Hit the full post for other suggestions on cutting down what you consume, and remember to eat and drink slowly as well, whatever size of vessel you use.
Eat Less Without Realizing It [Oprah.com]