I am looking for the best way to add a phone number field to the standard site wide contact form in Drupal 6.  I have looked at Webform which will work, yet I really don't need the submissions stored.  I have also read the description of the Contact forms module, which appears that it may work, but also seems like a lot of overhead for the little feature I need.

I'm curious if anyone can suggest a simple light weight method of adding a single additional field to the site wide contact form?

Thanks,