Some sort of "roadmap" feature. The ability to manually mark a revision as being relevant to the ticket (like the auto feature you have). When a revision (or revisions) are related to a ticket display a prominent, separate, link(s) to them in the ticket. Due date and importance for tickets. Highlight the importance in the list view (e.g. urgent = red etc.). When a revision is "tagged" in the mercurial repository create a link to a "changelog" that lists fixed issues for that tag name (if it exists: version or milestone - or even a separate tagging system).

That's just a few off the top of my head. (sorry; I always seem to be dissing you guys :( not intentional)