A number of folks have blogged about this over the last few weeks - but since I found myself recommending it to 3 different people today (and I know that two of them read this blog), I figured that I should post it myself as well.
FotoVision is a suite of applications that allow you to organize and manipulate digital photos and share them on a web site. What's cool about it is that it's a good example of reusing web services across different front ends. You get a Windows Forms client, an ASP.NET web site that exposes some Web Services, and a Pocket PC application.
You also get the VB .NET source code for all the applications, plus a lot of good whitepapers.
Check it out!