Например, на ибэй_ком при регистрации, поля ввода телефонного номера. =)
<span class="fv-tw" style="background-color: transparent;"> <input id="dayphone1" class="fv-mg" type="text" a="1" t="1" maxlength="3" title="Telephone number, area code." size="2" name="dayphone1" style="background-color: rgb(255, 255, 255);"> <input id="dayphone2" class="fv-mg" type="text" a="1" t="1" maxlength="3" title="Telephone number, exchange." size="2" name="dayphone2" style="background-color: rgb(255, 255, 255);"> <input id="dayphone3" type="text" a="1" t="1" maxlength="4" title="Telephone number, last four digits." size="3" name="dayphone3" style="background-color: rgb(255, 255, 255);"> </span>