Monitor Multiple Selects for Change but not default value, Using JavaScript?

How do I monitor multiple selects, using JavaScript,  to see and get the value, if it has changed and it is NOT "Choose one" (top selection with no value) ? I can not add "onchange" event directly to the select  mark-up.

 

<select id="mainForm1" name="mainForm1" size="1">	<option value="">-- Choose one --</option>
	<option value="EMPLOYED">Employed</option>
	<option value="SELFEMPLOYED">Self-employed, Business owner</option>
	<option value="UNEMPLOYED">Not employed, Homemaker, Student</option>
	<option value="RETIRED">Retired</option>
</select>
<select id="mainFormA" name="mainFormA" size="1">	<option value="">-- Choose one --</option>
	<option value="val1">First Selection</option>
	<option value="val2">Second Selection</option>
	<option value="val3">Third Selection</option>
</select>

FYI.. I nnderstand how to do it for a single select but I'm wondering if there is an easier way to handle multiple selects at  the same time?
Thanks!