[development] CCK Checkbox Matrix module?

Hi, I was wondering if anyone knew of a CCK module that could make a field give a matrix of checkboxes. I have attempted to create a mock of what I am looking for here http://www.haletechnology.co.uk/cck_matrix_checkboxes.html The Matrix module <http://drupal.org/project/matrix> would be great, except the matrix is made up of text input fields, instead of checkboxes. Any suggestions would be appreciated. Thanks robin