Getting Logged in user info

[CrimsonKing]

I'm looking to write a PHP script, independent of the forum, that can tell me whose logged on right now.
I have two ideas, one would be through cookies somehow, the other through $bbuserinfo[username], but i know very little about either.
If someone could either tell me which is smartest, and maybe point me in the right direction INFO wise, i don't mind doing the work myself.

Edit: whoops, that used to be on-line, i want logged on

[Xenon]

you have to require global.php into your script.

then you can use the $bbuserinfo array, which would be definitly the best way