After Google Chrome, Opera is my secondary browser and I use it very frequently. I use Opera to visit websites and check on stats among other things. Now, many of the websites I visit are news sites which have auto-refresh turned on. Sometimes, this provides me with a bad experience since the page auto-refreshes while I am in the middle of reading an article.
On the other hand, I find it unproductive to reload stats pages every time I want to see new data. Thankfully Opera has a nice little which will allow you to stop auto-refresh on certain websites while allow you to refresh certain websites after a time-interval.
In order to stop a webpage from auto-refreshing, right click on that page and select "Never" from the "Reload Every" submenu. On the other hand, you can use the same menu to also auto-refresh certain webpages after a certain time interval.
This feature is pretty useful since it is built into the browser itself and does not require third-party extensions. Pretty neat and useful.
Further Reading: Auto-refreshing of webpages is done through a meta tag, you can read more about it here.