<script type="text/javascript">
function clickclear(thisfield, defaulttext) {
if (thisfield.value == defaulttext) {
thisfield.value = "";
}
}
function clickrecall(thisfield, defaulttext) {
if (thisfield.value == "") {
thisfield.value = defaulttext;
}
}
</script>
<input type="text" name="myfield" onclick="clickclear(this, 'default text')" onblur="clickrecall(this,'default text')" />