Custom RSS application

The task is to build an application to collect and export details from a number of RSS feeds. The data then needs to be exported to a CSV file with user-mapped fields. I am receptive to a number of possible solutions. The application could be a stand-alone Windows application with GUI, a cross-platform application, a web app or even a script for Excel 2003. Existing open source tools and apps can be used. It should be a simple process for users to add / remove feeds, and also to change the mapping onto the exported CSV file.