I wrote this post on my personal blog about how cool I thought the Xero accounting application is. With the number one thing being collaboration, being able to provide your accountant, book keeper, ad visor, coach whoever real time access to your financial info changes the way small to medium enterprise currently do business.
Philip Fierlinger from Xero posted some excellent slides about agile development and getting real. I don't know if you really needed to use flash, I'd prefer to just go straight to HTML but whatever works for you as long as it quick and easy.
If you are interested you can see Phil in Sydney at the Oz-IA conference