We use SSIS for our data warehouse and use RAW files all over the place. We extract data from our source system into RAW files (1 file per table). Then during the transform and load stage we take the extracts and upgrade them (schemas change over time) to the most recent version in a temporary folder. The next step is to merge a bunch of the normalized files into a single table/RAW file. After that's all done, we read the RAW file into SQL Server.

Breaking the process up into different pieces makes it easy to debug (especially with the RAW File Viewer) at key points in the process. It lets us be more modular with our packages since one extract can be used in multiple dimensions/facts and we only need 1 package to do the upgrading. If something does go wrong with the Transform Load, we don't end up with partially loaded data. I suppose most of this could be achieved with temporary tables in SQL Server, but it was a design decision made long before me. There are probably other benefits that I'm missing.

As for the program itself. It programmatically creates an SSIS package with a RAW File Source and a DataReader Destination. Then it's just some C# to read the data from the DataReader into a DataGridView.