Currently, we have 5 types of custom field : text, number, date, document and Select List.

What we would like is a new type: User List.
It would be a Select List where the options would be populated by users from a particular group.

This would allow an arbitrary number of user associations with a given issue (more than "reporter" and "assignee").

More importantly, the association could also automatically add the selected user as a "Watcher" thereby subscribing them to the notifications defined by the notification scheme.

Currently, there are a number of people asking for multiple assignees - this could satisfy that.

What we want to do in particular is that when an issue is raised, we want to associate a "Business Analyst" who will be responsible for tracking this issue to completion. This business analyst will want notifications (without having to manually "watch")
We also want to associate a particular tester (usually a user) who will also be folowing the issue (notifications)- providing domain knowledge when he/she sees it is required.

-Nick