I should preface this post, as many users have been, by expressing my thanks to the developer(s) for version 1.7 - I was particularly happy with the frontend changes.
On that note, I have a bit of a pie-in-the-sky suggestion, which comes in two flavours...
Seeing the development of some really interesting themes, such as (jay_pick's Responsive theme), I imagine that some sort of customisable theme architecture might be a good way to encourage users who may be considerably stronger designers than software developers to produce new themes.
Similarly, seeing the popularity of developing "mods" to implement small, optional features, I imagine that some sort of plugin architecture might be a good way to manage "feature creep" (which, to be fair, is so far from being an issue for me, even with some of the new features, like SLA, which we don't use at all in my workplace), and to encourage the less code-savvy community to try new osTicket mods and participate in their evolution.
Without wanting to suggest that osTicket has much in common with Wordpress, I would have to say that Wordpress' treatment of themes and plugins is very close to what I have in mind with my two suggestions. I should also confess that I'm already sure that the implementation of either one of these suggestions would be immensely non-trivial. What do other users think?