Tendiras que crear un parametro en la funcion de changeSource y llamar el campo algo así
Código html:
Ver original<FORM name="formulario" ACTION="" METHOD="POST"> <img border="0" onclick="test.location.href='http;//www,google,es/';document.getElementById('test').frameBorder=1" src="world.jpg" width="16" height="16"><img border="0" src="black.jpg" width="16" height="16"><img border="0" onclick="test.location.href='http;//rampage-clan,ukgame,co,uk';document.getElementById('test').frameBorder=1" src="group.jpg" width="16" height="16"><img border="0" src="black.jpg" width="16" height="16"><img border="0" onclick="test.location.href='http;//space,widicommunity,com';document.getElementById('test').frameBorder=1" src="heart.jpg" width="16" height="16"><img border="0" src="black.jpg" width="16" height="16"> <INPUT TYPE="text" NAME="web" size="100"> <img border="0" onclick="changeSource(document. formulario.web.value)" src="folder_go.jpg" width="16" height="16" TYPE="submit" /> <script type="text/javascript"> function changeSource(url)
{
document.getElementById("test").src=url
}
<iframe src="http;\\www,widicommunity,com" frameborder="0" name="test" id="test" width=100% height=800 border="0" align="absbottom" marginwidth="1" marginheight="1"></iframe>