I think timebridge does a pretty good job with its UI to schedule multiple people with multiple options/constraints.

The basic matrix grid calendar with toggle between day/week/month is kinda like the QWERTY keyboard of time interfaces. You really don't have much choice but to use it as a foundation, otherwise you'll confuse the heck out of people and adoption will be low.

That said, there are 2 UX ideas I'd like to see, but haven't yet seen in any system.

1. A logarithmic view on the time axis (or a fish-eye lens). You are generally interested in today at the resolution of hours, this hour at the resolution of minutes, the next few days at day-sized chunks and then the next month, next quarter, next year, next 3 years, next 5 years in equal visual blocks. Not useful for something like equipment/room reservations, but great for planning/forecasting type applications.
2. Some use of Allen's temporal interval calculus formalism that allows you to think in terms of qualitative relationship terms like before/after/during etc. (there are 13 basic qualitative relationships). Google it, email it, or read my book (Tempo, Chapter 2) if you're interested. I think very sophisticated scheduling UIs can be built using it, with a very elegant approach to expressing constraints in particular. Particularly true for resources that must be managed collaboratively in time (eg. both the video camera and microphone rig must be present in the studio for you to use it, if somebody has borrowed one or the other, reserving the studio would be of no use to you, or you may care about one but not the other... easy to express all this).

In terms of other UI possibilities, I don't think other familiar starting points have been exploited enough (clock faces, "take a ticket" queuing models, alert-based just in time scheduling).

Time is a very rich dimension of experience. We've barely scratched the surface of how to interact with it in software UXes.