Interesting. Tried, but no luck in Netscape.
This works in IE.
<script>
function print(msg) {
document.form1.box.value = msg;
}
</script>
<img src="t_cost.gif" width="298" height="35" alt="" border="0" usemap="#hej"><map name="hej">
<area alt="Nothing" coords="182,5,239,21" href="hello.html" onMouseOver="print('goddag')" onMouseOut="print('')">
</map>
<form name=form1>
<input name=box>
</form>