Smashing Magazine has a great article about different digital data visualisation techniques:
"There is a variety of conventional ways to visualize data - tables, histograms, pie charts and bar graphs are being used every day, in every project and on every possible occasion. However, to convey a message to your readers effectively, sometimes you need more than just a simple pie chart of your results. In fact, there are much better, profound, creative and absolutely fascinating ways to visualize data. Many of them might become ubiquitous in the next few years."
From a practical point of view, I really liked newsmap, "an application that visually reflects the constantly changing landscape of the Google News news aggregator. A treemap visualization algorithm helps display the enormous amount of information gathered by the aggregator".
BTW If you are interested in Web design, then its worth exploring the rest of Smashing Magazine.