However good the figures in a worksheet are, they aren't as easy to understand as they are when shown in a chart. The charting module in Excel 2007 has been heavily reworked and has a much wider range of effects available. At the same time, if you make use of the presets and styles available, it's a lot easier to setup good-looking and informative charts with little time and effort.
In Excel 2003, chart effects were pretty basic. You could do 3D bars and pies, add legends and axis titles, but that was about all. The features in Excel 2007 go a lot further. When you highlight the data in an Excel worksheet and insert a chart from the Insert ribbon, in most cases the program correctly detects the data series you want to chart and even uses the column headings as its data labels.
There are a lot of style choices in the Charts section of the Insert Ribbon and the basic look of the chart is decided here. There are the different types of chart: column, line, pie, area and within each of those, 2D and 3D styles and different shapes for the data elements, like columns or cones for the bars in a bar chart.
Once you've got the basic chart on top of the worksheet, there are plenty of ways of enhancing its look, such as introducing transparency, shadows, bevels and lighting effects. You might, for example, have two series of figures depicted in a 3D bar chart, where whichever set you put at the back has bars totally obscured by the corresponding bar from the other set, in front. One way out of this is to make the front set of bars semi-transparent, so you can still see all the bars in the set behind.