Flash charts are preferred over static image chance since they the former are visually more appealing and data-driven - if the underlying data changes, you don't have to redraw the chart.
The disadvantage of Flash charts is that they require Flash plugin and therefore the charts may be visible inside email messages or news readers since they do not render Flash.
Zoho Sheet offers an elegant solution to this problem - their graphic engine lets you create dynamic charts and graphs in image format which you can also resize and embed in your blog pages just like any other web graphic.
Here's how you do it:
1. Create a Zoho sheet and fill it with tabular data.
2. Click the Chart icon and select the chart type [Column, Bar, Stack, Pie, Bubble, Line Charts and so on]
3. Once you have the chart, resize it to fit your site layout and click the "publish" link on the chart. This will create a public URL of that chart that points to a PNG image.
Use that anywhere in message boards, emails, blogs, etc. While this image may look static, it's actually drawn with the latest data in your spreadsheet - if that changes, you will see a new image.
Google Docs & Spreadsheets have also added impressive charting capabilities but they do not allow embedding yet though you can download the rendered chart from Google Docs as an image.