Work flow is a concept often bantered about when discussing collaborative software, but it applies to procedural management software as well, even if only one person is using it.
At the moment, I'm the only one using our PBooks application to manage our internal finances, but I'm beginning to see a work flow emerging which can keep track of invoices, payments, and deposits. This will be very helpful to me, and I imagine many other business managers.
Since not every business is run the same way, I plan to keep work flows as customizable as possible. I will likely use XML for this, and will examine how Trac provides for customizable work flows.
Of course I welcome any suggestions in the mean time! :-)