I have found the following utilities to be amazingly handy:
autojump is a faster way to navigate your filesystem. It works by maintaining a database of the directories you use the most from the command line.
ranger is a console file manager with VI key bindings. It provides a minimalistic and nice curses interface with a view on the directory hierarchy. It ships with "rifle", a file launcher that is good at automatically finding out which program to use for what file type.

If you use emacs there is also an emacs mode that emulates functionality. This and similar other utilities are outlined in my post on the topic.
github/hub: Wrapper for git command that augments it with github aware options. I use it in conjugation with many useful git aliases.
peco Interactive filtering tool to quickly find entries in lists of items
peco can be a great tool to filter stuff like logs, process stats, find files, because unlike grep, you can type as you think and look through the current results.

The aforementioned git aliases link also illustrates usage peco with git to quickly switch to recently accessed branches using git cob.
A code searching tool similar to ack, with a focus on speed.
