GNU parallel is a shell tool for executing jobs in parallel locally or using remote computers. A job is typically a single command or a small script that has to be run for each of the lines in the input. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables. If you use xargs today you will find GNU parallel very easy to use, as GNU parallel is written to have the same options as xargs. If you write loops in shell, you will find GNU parallel may be able to replace most of the loops and make them run faster by running several jobs in parallel. GNU parallel makes sure output from the commands is the same output as you would get had you run the commands sequentially. This makes it possible to use output from GNU parallel as input for other programs.
Vimv is a utility to help rename various files at once using a text editor. It opens the list of files in a directory inside a text editor (vi by default). Then, any changes made in the editor will be reflected in the filesystem (the files in the directory will be renamed to the names saved in the editor).
ribbil is a wireless network manager designed for power users. It purposes is to provide an easy way to connect to wireless networks from a console under GNU/Linux, using wpa_supplicant and wireless tools. It can be used through the command line directly or through its curses interface.
Clicco is a tool for constructing command line commands based on saved configurations. It is ideal if you have difficulty remembering the exact commands, arguments, or argument values for various situations, as you can save commands with various argument choices for future use along with a description.
s6-portable-utils is a set of tiny general Unix utilities, often performing well-known tasks such as cut and grep, but optimized for simplicity and small size. They were designed for embedded systems and other constrained environments, but work everywhere. Other sets of small utilities are usually system-specific; for instance, the (otherwise excellent) BusyBox project only works on Linux.