If you need to visualize some data and the graphs available in Excel aren't doing it for you, check out Track-n-Graph. It's a free online service that allows you to create graphs of just about any imaginable type. The results are certainly better looking that the graphs you get out of Excel. And there are sharing capabilities. So if you are working with others, or you need to publish your results to your own site, it's easy to get your work out there. It's very web 2.0, so of course it's in beta. But it's still a pretty solid product at this point.