What "tags" are allowed on what page in the Server Configuration fields? For example [username] is allowed on the JailKit configuration tab and [system_user] is available for the FastCGI tab. It would be helpful to list available options also on the bottom of the page or in a popup maybe.
At the moment all allowed tags are used in the default paths. So if a placeholder is not used in the default path, then it does not exist.
Well like in Website Path I wanted to use /var/www/clients/[username]/[website_domain] instead of the default. This doesn't work as it created a directory called [username].
Thats exactly what I told you above. In the default path which is in this field, there is no placeholder [usename], so this means that you can not use [username] as placeholder in this field. There is a feature request to add more variables to the paths. If you like to see such a feature in ISPConfig, then you should vote for it in the bugtracker: http://bugtracker.ispconfig.org/index.php?do=details&task_id=674&project=3
I thought you said that the ones already in use can be used. Sorry about that, but the [username] one is in the Jailkit so I figured it could be used in another area.