It would be incredibly helpful (for us) to be able to pass arguments to the URL specified in a Screen cell with type URL.
For example, Screen -> Cell -> Item type (Url) -> http://myzabbix.com/info.php?hostid=
The best way, would probably to copy the POST/GET variable from the main screen url. If you then have other dynamic items like a graph, then hostid is a variable that is known.
Why? This way we can make dynamic host screens, including separate webpages/systems with specific information like documentation, or simply data for a particular host presented in ways that are not directly supported in zabbix.