Last Saturday "leap second" adjustment caused issues with many online sites: "Leap second bug wreaks havoc across web".
Google's SRE team posted a nice blog post on how they fixed leap second issue: "Time, technology and leaping seconds" by "leap smear", where they change duration of each second reported by NTP depending on "leap second" is added or subtracted. Wondering whether similar techniques can be applied to Stratum 0/1 NTP servers so that the rest of the people don't have to worry about leap seconds in future?