Código PHP:
Año:
<select name="fecha_ano">
<?php foreach (range((date('Y')-5), (date('Y')+5)) as $year) { ?>
<option value="<?php echo $year; ?>"><?php echo $year; ?></option>
<?php } ?>
</select>
Mes:
<select name="fecha_mes">
<?php foreach (1, 12 as $month) { ?>
<option value="<?php echo $month; ?>"><?php echo $month; ?></option>
<?php } ?>
</select>
Día:
<select nam="fecha_dia">
<?php foreach (1, 31 as $day) { ?>
<option value="<?php echo $day?>"><?php echo $day; ?></option>
<?php } ?>
</select>