StatTrends (formerly "Graph Maker") is a free application for creating interactive charts and graphs. The supported visualizations are:Interactive bar and column charts,Interactive scatter plots (bubble chart),Interactive time series graphs and Interactive bullet graphs.
Using StatTrends you can create your own bubble graphs, show a third variable through the bubble size, animate them over time, and use 'trails' to visualize trends for individual bubbles. In addition to these features you can create variables groups and select these groups using the drop-down menu. It is also possible to create custom groups on-the-fly. This is useful for zooming into bubbles or variables of particular interest, and StatTrends allows you to easily and intuitively switch between different groups as well as from one type of graph to another while maintaining your selection.