add-on or plugin in order to enhance JQL in Jira OnDemand

Here an example:
I have one issue of type "Task".
Users may add a subtask to this issue of type "ShowStopper".
I´d like do filter all Tasks that does not have a subtask "Showstopper" with status "Open" associated with it.
There is a lot of plugins in Jira that extends JQL but it seems NONE of them are available do Jira OnDemand which is a shame.
I think this is a very important feature and it´s absolutely necessary.

In my point of view this is very basic and everybody that wants to use Jira OnDemand for serious will need this kind of JQL extension.

Am I the only one that is requesting an extension to the very simple JQL syntax bundled with core jira?