[totaltec]

Never done it, but it should be easy.

Here is the template in question: /common_files/modules/Gift_Certificates/customer/giftcert.tpl

And here is the original code:

<td>
          <input type="text" name="amount" size="10" maxlength="9" value="{$giftcert.amount|formatprice}" />
          {if $min_gc_amount gt 0 or $max_gc_amount gt 0}
            {$lng.lbl_gc_amount_msg}
            {if $min_gc_amount gt 0}
              {$lng.lbl_gc_from} {include file="currency.tpl" value=$min_gc_amount}
            {/if}
            {if $max_gc_amount gt 0}
              {$lng.lbl_gc_through} {include file="currency.tpl" value=$max_gc_amount}
            {/if}
          {/if}
</td>

See the <input> Just change it to a <select> with the same name. http://www.w3schools.com/tags/tag_select.asp