Data is often displayed poorly, making it difficult to see what is important. When data is displayed well the important facts should leap off the page and into the viewers mind. Edward Tufte is an expert on this topic with great books. If you have not read them, you should: Beautiful Evidence, The Visual Display of Quantitative Information, Envisioning Information and Visual Explanations.
Smashing magazine has some nice examples of good display techniques in Data Visualization: Modern Approaches. I don’t like all the examples they show but it does provide some help by showing some creative ways to display data.
Related: Edward Tufte’s new book: Beautiful Evidence – Great Charts – Data Visualization Example