When my daughter was young, she was a great eater. She'd eat whatever I put in front of her with gusto. I naively thought that her eating habits would last, but unfortunately as she entered the toddler stage she also became a picky eater. I would struggle to get her to eat two or three different foods in a day, especially if they were not white.
I read in a parenting magazine about "Eating the Rainbow" - being sure to eat foods of different colors each day. This ensures a well-balanced diet, since foods of different colors tend to contain different nutrients. It is also an easy way to think about introducing variety into your grocery shopping and your diet without having to do a lot of research about nutrition contents.
We made a big chart on a piece of poster paper with the days of the week down the side and the colors of the rainbow across the top. We combined blue and purple, since there are not a lot of blue foods out there. We cut out pictures of healthy foods from magazines and glued them to our chart, and then we had it laminated at our favorite office supply store.
As my daughter eats a food, we check off the appropriate box on the chart. As the day goes on and she is looking for a snack, I remind her to check and see what color she is missing, or I might suggest that it's time to "eat a yellow (or whatever)". Once she's eaten her colors, she's free to have whatever healthy snack she wants. Since it's laminated, we use a dry erase marker and are able to re-use the chart each week. We've had great success with this technique, since it's fun for her and easy for me. If you give it a try, please post a comment and let us know how it goes!