How about a visual analog round clock where people can drag the hour hand to a certain point, and choose to create a range by dragging and so extending the time slice with another hour hand.
Thanks for the suggestion - it's something we've considered; the issue with our tests to date has been getting the minute-to-minute fidelity with a circular interface (plus it's actually quite hard to drag something accurately in a circular motion). But we should revisit this all with fresh eyes - and the idea much appreciated!