The list of all StackExchange sites (at https://stackexchange.com/sites?view=list) can be sorted by Traffic, Oldest, Newest, Questions, Answers, Percent Answered, Users, Questions Per Day and their Name.

The Oldest and Newest options are opposites, but for every other sorting option no opposite sorting method exists. I suggest that there should be another toggle for reversing the lists order.

This toggle could be located next to the other sorting options: