Spectre:

Tcl actually, but I guess Expect would run it too.

(They're basically the same thing, expect is just the tcl interpreter with a few more functions added)

All one line:

<?php $str = '<?php $str = \'X\'; echo substr_replace($str, addslashes($str), 14, 1); ?>'; echo substr_replace($str, addslashes($str), 14, 1); ?>

ZiggyFish:

<?
    echo htmlentities(file_get_contents(__FILE__));
?>

The OP never mentioned it had to be a quine (it looks like they have names for this (WTF)). 

A BASIC quine without using LIST:

1 READ D$,S$:PRINT S$:PRINT D$;SPC(1);D$;MKI$(8748);S$
2 DATA 2 DATA,"1 READ D$,S$:PRINT S$:PRINT D$;SPC(1);D$;MKI$(8748);S$

An mIRC quine:

//var %q $(| echo //var % $+ q $!( $+ %q $+ ,0) %q,0) | echo //var % $+ q $!( $+ %q $+ ,0) %q

heres my first attempt at a real quine.

sql proc:

create proc q as declare @d varchar(500) set @d = 'create proc q as declare @d varchar(500) set @d = xyx select replace(replace(@d,char(120),char(39)),char(121),@d)' select replace(replace(@d,char(120),char(39)),char(121),@d) 

fun with data uris:

data:text/html,<script>alert(location)</script>