Using a combo box for a ajax search

I have a ajax search set up that works very well but I can only search
one thing.

code im using

Search:

<%= observe_field ‘search_form’,
:frequency => 0.5,
:update => ‘results’,
:url => {:controller=>‘ratings’, :action=>
‘get_results’},
:with => “‘search_text=’ + escape(value)”,
:loading =>
“document.getElementById(‘spinner’).style.display=‘inline’”,
:loaded =>
“document.getElementById(‘spinner’).style.display=‘none’” %>

Where action is I was wondering if I could set up a combo box so I could
switch between methods in the controller and whats selected in the box
would be used for the action. I would can the moethods to make it more
meaning full for the user.