[nobr]Hope this will help you..in my answer there is one text box and one Submit button...when I press Submit button it will fire JavaScript and open another JSP file and send textbox value into that file..
<html><head>
<SCRIPT language="javascript">
function sndUserCheck(action)
{
window.open('pagethatyouwanttoopen.jsp?UserName='+action, 'Sample', 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,copyhistory=no,width=635,height=360');
}
</SCRIPT>
</head>
<form action="yourpagename.jsp" method="post" name="form1">
<input type="text" name="username" value="" autocomplete="off" size="15" maxlength="10"><BR><INPUT TYPE="button" VALUE="Check Availability of This ID" onClick="sndUserCheck(document.form1.username.value);">
</form>
[/nobr]