One of the easiest ways to sneak an extra serving of veggies into your day is to add some green to your fruit smoothie. I don't notice any difference in the taste, except an inherent "freshness" that I really enjoy. Here's my favorite fruit smoothie, which gives you at least one serving of veggies, and also a good amount of protein. (I try to include protein in most of my meals and snacks, because protein can prevent you from becoming hungry too soon.)
Start with about a cup of frozen strawberries, add a cup of yogurt, and a bit of liquid to get the blender going. Add some Splenda or sweetener of choice, along with a splash of vanilla and a bit of cinnamon. Add a bunch of spinach--one or two big handfuls. Blend until very smooth. Remember what you learned in your quilter's color class--red and green make brown. It tastes just like a strawberry smoothie if you don't look at the color!
If you want a pretty green smoothie, use spinach along with banana and pineapple--lime green! Add some vanilla protein powder to up the nutritional value.