We have a demonstration which you can try, without needing to use one of your own spreadsheets. This is in Less Excel, More Components, a 4-page presentation showing the Repository working with Excel. The final section, Try for yourself, links to the demonstration downloads and explains how to run them.
If you are interested in use with Google Spreadsheets, please read Spreadsheet Components, Google Spreadsheets, and Code Reuse, a 3-page feature with screen shots showing the Repository working with Google Spreadsheets.
The ideas behind the Repository are explained in Spreadsheet Components For All, a paper presented to the European Spreadsheet Risks Interest Group in July 2008. There's a recent (21st January 2009) summary in the Dobbs blog posting The Spreadsheet Parts Repository for Excel and Google Spreadsheets.