It can't be done with the FP form handler (since the "To" address has to be
an email at the same domain as the hosted site eg (e-mail address removed) where
your site is
www.yourdomain.com), but using third party email processing
scripts you can do this.
Try the FormMail at Matt's Script Archive etc.
The script uses a hidden field for the "To" information (which would usually
be yourself) but you can adjust this to make the "To" field a drop down box
instead.
If your idea is to have the "contact" form with the "to" drop down box being
heads of department in a business eg "Accounts" or "Administration" or
"Executive Director" or "Helpdesk" then you can do it, with a thirdparty
script.