I am a big fan of analogue clocks because they show the passage of time, rather than a single point in time like a digital clock. I encourage my students to wear analogue watches, and I utilize analogue clocks and timers during therapy sessions. Even my toddler has responded well to a timer to understand how many minutes are left to play before dinner, like the Time Timer shown above (http://www.timetimer.com/). I just found out there's an app for the iPhone with a Time Timer on it! I'll have to check it out... For kids struggling with transitions, like finishing playtime before bathtime, completing piano practice, or working on homework assignments, the clock can give them a visual countdown of how much time is left.
*One more note, the homework chart above has a "To Do" side and a "Done!" side. The pictures help a child who needs visual reinforcement to stay on task. The pictures have velcro on the back, so the child can manipulate their own list. Once they complete their homework tasks (or chores, etc.) they can have free time or toy time. I usually let the kids decide the order of tasks and create their own "To Do" list. Here's another example: