The easiest way into the dialogs which govern the look of a chart is by right-clicking with the mouse on the components of the chart. Right click on the columns in a bar chart and you're offered the Format Data Series dialog, right-click on the legend and it's the Format Legend dialog, click on the background and it's Format Chart Area. The Format dialog is modeless, so stays on the screen while you work, switching content as you click on the different chart elements.
Again, chart design can be approached at the macro level, where you apply preset colour schemes to the chart background, for example, or at the micro level, where you adjust the colours that make up a linear fill to get exactly the right look. There's opportunity here for introducing house styles, too, so you have a unique look to all your charts, but one which can be repeated from one to another within the same report.
It's worth spending some time familiarising yourself with the controls available through this dialogue on a sample chart, so you can see how adjusting sliders and turning options on and off affect the look of the columns, axes and labels.
Since the charting tools have been rewritten pretty much from scratch, Microsoft has taken the opportunity to incorporate them in Word and Powerpoint, too. This means you can cut or copy a chart created in one application and paste it into another, keeping it as a live chart, rather than just a picture. Sharing feature-sets like this makes it far easier to move between applications when working on multimedia projects, such as creating a presentation from a paper-based report.
Microsoft has not just rewritten the charting module within Excel 2007, but has also reworked WordArt, its fancy text tool. In fact, it appears to have gone further with this in Excel than in Word 2007, which still uses the older, less flexible tool. Create WordArt text in the new Excel and you can adjust the outline, fill and 2D and 3D effects independently and create a huge range of different special text.
WordArt can't be used within cells, but stands in a layer on top of the worksheet, as charts do. You can produce some very attractive report titles and other specially formatted objects using WordArt, though you do wonder why it hasn't been implemented in Office's specialist text applications, Word and Publisher 2007.