When I install Win7 on a computer most people are asking to see the common Windows Clock and Calendar on the Gadget Sidebar. They are nice but are missing some so useful features like an embedded stopwatch in the clock gadget and a timer in the calendar gadget. I would like to see a Clock Gadget with the possibility of setting as many stopwatches as I want and to be able to trigger any Apps when the time is up. And for the calendar, why not the possibility to trigger an audio file or pop up a text box or trigger an App when a date and time occur. That, I would really like to see.
I don't know how complex programming would be involved but I bet it would be a winner!