Countdown and count up timer viewable in the chat

Some of my players have a tendency to plan an action, in game, for a long time. I have, in the past, put a countdown timer from the internet on them and informed them when time was up. This works well but at times it would be useful to have a timer visible in the chat so I need not remind them of the timer along with the other duties as DM. It would also be useful to have timer that counts up as well. Perhaps this could be implemented or is there a way to show the internet timer to the PCs that already exists?

If you have PRO membership, then the Combat Master API allows you to set conditions that expire after a certain number of combat rounds. When their turn comes up, any counters for their character are shown in the little "your turn" announce box that appears in the chat window.