It would be useful to provide certain users from certain companies a view of all tickets from other companies.
For example, we support our sales guys' customers directly. What we get a lot of requests for is updates to the tickets which they cannot view because they don't have access to their customers' tickets.
If there was an additional field which we could add multiple companies to, maybe with a comma delimiter, we could provide them full view of all tickets within select companies.
We also have 3rd party suppliers who would also like to see status of tickets relating to their relevant customers.
Perhaps another way to look at it might be if the 3rd party was Cc'd within an email, there would be an option within the ticket to allow that person access to the ticket, as if they were the requester but with reduced privileges.

