I don't know exactly where to put this

[musclenexus]

I sometimes see an image in people's sigs on boards that shows me my IP address. How the hell is that done?

[assassingod]

They use GD to generate $REMOTE_ADDR (IIRC that's the variable for IP) onto the image

[qxh]

Information on image (GD) functions:
http://www.php.net/image

Some vars:
$_SERVER['REMOTE_ADDR']; // ip address (111.222.333.444)
$_SERVER['REMOTE_HOST']; // host name (proxy.aol.com)
$_HTTP['referrer']; // will show the page they're viewing in a sig