I like the debian-goodies package:

Description: Small toolbox-style utilities for Debian systems These programs are designed to integrate with standard shell tools, extending them to operate on the Debian packaging system. . dgrep - Search all files in specified packages for a regex dglob - Generate a list of package names which match a pattern . These are also included, because they are useful and don't justify their own packages: . debget - Fetch a .deb for a package in APT's database dpigs - Show which installed packages occupy the most space debman - Easily view man pages from a binary .deb without extracting debmany - Select manpages of installed or uninstalled packages checkrestart - Help to find and restart processes which are using old versions of upgraded files (such as libraries) popbugs - Display a customized release-critical bug list based on packages you use (using popularity-contest data)

and also moreutils, which is basically awesome pipe tools on wheels:

 Description: additional unix utilities This is a growing collection of the unix tools that nobody thought to write thirty years ago. . So far, it includes the following utilities: - sponge: soak up standard input and write to a file - ifdata: get network interface info without parsing ifconfig output - ifne: run a program if the standard input is not empty - vidir: edit a directory in your text editor - vipe: insert a text editor into a pipe - ts: timestamp standard input - combine: combine the lines in two files using boolean operations - pee: tee standard input to pipes - zrun: automatically uncompress arguments to command - mispipe: pipe two commands, returning the exit status of the first - isutf8: check if a file or standard input is utf-8 - lckdo: execute a program with a lock held Homepage: http://kitenet.net/~joey/code/moreutils/