z
Tracks your most used directories, based on 'frecency'
...The rank of each entry is incremented every time it is accessed. When the sum of ranks is over 9000, all ranks are multiplied by 0.99. Entries with a rank lower than 1 are forgotten. Frecency is a portmanteau of 'recent' and 'frequency'. It is a weighted rank that depends on how often and how recently something occurred. As far as I know, Mozilla came up with the term. To z, a directory that has low ranking but has been accessed recently will quickly have higher rank than a directory accessed frequently a long time ago.