<form>
<input type="text" value="Your Name" name="name" onblur="if (this.value == '') {this.value = 'Your Name';}"  onfocus="if (this.value == 'Your Name') {this.value = '';}" />
</form>

This just replaces the default value of a form element.  Then it bring it back if you click away.

Replace on Focus (form)

form

HTML