http://ezgif.com/maker can rotate based on time as a shitty solution, but makes a long gif instead of switching the image and it's based on when the gif is loaded not the original image so it's only really useful for 1-30 second duration rotations. It doesn't do anything you can't just do yourself in a variety of programs.
If you really want stuff to change on that kind of timeframe, host them on your own server. javascript/jquery/php can all set up a rotation based on time easily either based on server time or client time.