Your tool works perfectly because you can set it to intervals as short as 1 second and it still refreshes whereas others either don't seem like they refresh or tell you 5 seconds is the minimum

这个显示时间的设计很棒，但要是能让用户自定义标签的字体大小和颜色就更好了。最好能放在地址栏，切到设置了定时的标签就显示；切到别的标签就隐藏。缺点是重启之后定时就没了，手动刷新页面后倒计时不会重置。。。

This is the best one I've found. It shows the time remaining for the pages that are set to auto reload. You can also set an exact time which is awesome.