Everyone has Microsoft Excel, so why don't more people use it for creating dashboard reports? Well, the consensus among the dashboard designers I spoke to seems to be that one can't get dashboard designs out of Excel that don't look like, well, dashboards made in Excel.
Yes, we've all seen those dashboards that are simply a collection of Excel graphs. Well, take a look at this nice dashboard layout:

Yes, that slick looking layout is done in 100% Excel. It's a dashboard Excel Template that is all set up and ready to point at your data. Use that link to check out the details.
Even Stephen Few likes the dashboard. See his blog entry in Visual Business Intelligence titled When Expensive Dashboard Software Doesn't Work, Do It with Excel.
Go Excel for dashboards!