So, if you want more than one value for a field, it's a problem.
Say you want a user to be able to enter an arbitrary number of email addresses/IM names/phone numbers/whatever on his profile. The "Allow multiple values" option in CCK is woefully adequate.
Aaron tackled this problem with aplomb (well, as far as Drupal allows) by creating a new CCK type for each field that we need to allow multiple fields on. We create a block view for it, then simply embed that view in the profile edit form.
