onclick -> ghost en input

<script type="text/javascript">
    function toggleDisable(elm){
        document.getElementById('pony').disabled = (document.getElementById('disable').checked)? true: false;
    }
</script>
<input type="checkbox" id="disable" name="disable" onclick="toggleDisable('pony')">
<input type="text" id="pony" name="pony" value="" />

<input type="checkbox" name="min_checkbox" id="min_check" onclick="document.getElementById('mit_text').disabled=this.checked">
<input type="text" name="mit_textfelt" id="mit_text">