or the old shot of a clock then disolve to a shot of the same clock hours later.
Little tip I picked up after doing it a 4 or 5 times... you dont have to wait there holding the camera while those hours pass.....you can just change the time using the dials on the back of the clock !
Man that second shot was shakey! ; )
But seriously its another way , depending on how you want to imply that passage of time, as Gary said a std dissolve is usually used to indicate the passage of time.