[Projektil]

..but i think it is relativly easy to find out how many members have been online today:

PHP Code:

$startTime ==  mktime (0, 0, 0, getdate('month'), getdate('mday'), getdate('year')  )
$endTime == mktime (23, 59, 59, getdate('month'), getdate('mday'), getdate('year')  )
mysql_query("SELECT * FROM user WHERE lastactivity>$startTime AND lastactivity<$endTime "); 


this should give you the number of users. i never tested it but you might want to start to build the hack for us.