Works Database Converter (WDC) converts old Microsoft Works Database (*.wdb) files (e.g. MS Works 3 and 4) into a spreadsheet compatible with all versions of Microsoft Excel.
I initially created WDC for my mother-in-law, who had found that, upon upgrading to Windows Vista, she could longer open the file that contained her database of Christmas card names and addresses. Microsoft Works was installed - it just could not open files from version 4 or earlier. (The suggestion from Microsoft's Knowledge Base was to find someone who had an old copy of Microsoft Works and ask them to export your file as a CSV file.)
Fortunately, I had some printouts of part of the database and was therefore able to reverse-engineer the binary file format over a couple of evenings.
For more, visit the Works Database Converter website.