sl takes the most common use of Unix ls, to display the files in a directory compactly in multiple columns, and makes it substantially more useful.

via: http://chneukirchen.org/trivium/2012-02-19

"Bookmark" directories on the command line, cd to them quickly.

Missed this. It makes the most useful app of recent years even more useful.

"Allows basic cvs style operations on Time Machine volumes." Great for quickly checking what Time Machine has been up to.

Interesting search tool built on top of Spotlight that lets you restrict queries in a simple CLI-ish way.

Tips on using mdfind, mdls, mdimport and mdutil.

Command line utility for playing audio files (anything that Quicktime can handle)