We recently switched from FogBugz to Jira, and one thing we used in FogBugz quite a bit was "virtual users" - these are not real users, but placeholders for a general category, such as "up for grabs".
Here is a more detailed description of a virtual user - the most important characteristic is that they do not use up a license seat:
A virtual user can't log on and doesn't use up a license. Its pupose is to allow assigning of cases to a group of people instead of an individual. For example, you could create an "Up For Grabs" virtual user that serves as a sort of work queue and owns a case until someone assigns it to themselves. Give it all of the email addresses (comma separated) of the users you want notified when a case is assigned to create a notification list.
Car I create a virtual user in Jira that does not take up a license seat?