I've got a series of checkboxes in my User Registration Form which I've augmented with the 'Profiles' module.

The user can pick any or all of the boxes, and he can also fill in a textbox called 'Other'.

I want him to select his primary choice in a listbox. I could prepopulate the listbox, but obviously Whatever in 'Other' will not be available for selection.

Can I take the contents of 'Other' and dynamically add it to the istbox?