Another Dan Griffin sample you might want to look at is the EC2 Console. I think his description from the first post in that category sums up his approach very nicely:
The purpose of the EC2 Console, like the other ones, is to demonstrate an attractive (WPF-based), novel, and useful application on Windows. In this case, we chose as our vehicle a helpful control panel for Windows developers who are new to cloud computing and would like to experiment with Windows Server, ASP.NET, and MS SQL on Amazon’s EC2 platform.
As it happens, Amazon already has an EC2 console (currently in Beta). But we’re going to differentiate ourselves from that in two ways. First, our EC2 Console will be specific to developers targetting Windows, and we can automate many administration tasks given that assumption. Second, our console (again, a WPF client app) will exhibit the kind of superior usability that is very difficult to achieve via the browser.
Client applications have many more advantages than just offline availability. Here's an application that's only useful when you're online, but is going to be a client application anyway. Follow along and see why.