Having recently having my eyes opened to Open Source, the first area I pursued was the Data Layer. I started with NHibernate, but it turned out to be a bad fit. SubSonic was MUCH better, but it didn’t support Oracle very well. I did start making changes to the SubSonic source to get it to work for us, but then the corporate gods heard “Open Source” and decreed that SubSonic had to go. Nevermind that we had spent five months using it. I was given two weeks to come up with a new, homegrown, data layer. Well, two months later, we had our data layer. It reads the Oracle tables, views, functions, procs and packages and generates classes that can read/write/execute as appropriate. It turned out pretty well and is delightfully easy to use.
Next, up, the UI. The chosen toolset is Telerik RadControls for ASP.Net AJAX. (My previous experience is with Infragistics Windows toolset, so this was an interesting transition.) Users wanted the grid to be multi-edit. Teleriks grid does not support this natively, but it can be configured and coded to do it. But that is for another post.
Now, we are investigating MVC and Silverlight. I am hoping that my posts here will be of benefit to some as I explore these new technologies.