yaspi (Yosi's Anti-Spam POP3 fIlter bot) is a POP3 mail-scanner specifically made to combat mail bombings caused by viruses (i.e. Swen). It connects to the POP3 server, inspects the messages, and deletes the infected ones without ever downloading them. Its most interesting feature is that it can automatically send abuse reports to the ISPs from which the infected mails originated.
getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types commonly found on Unix systems, as well as Windows LM hashes. On top of this, lots of other hashes and ciphers are added in the community-enhanced version (-jumbo), and some are added in John the Ripper Pro.
cw is a non-intrusive real-time ANSI color wrapper for common Unix-based commands. It is designed to simulate the environment of the commands being executed, so that if a person types 'du', 'df', 'ping', etc. in their shell it will automatically color the output in real-time according to a definition file containing the color format desired. It has support for wildcard match coloring, tokenized coloring, headers/footers, case scenario coloring, command-line- dependent definition coloring, and includes over 50 pre- made definition files.
VTAGS is a command line application that will generate a VI(M) compatible tags file for VHDL source files. This application will read standard VHDL'87 files. It should also parse later VHDL, but it only takes account of the basic parts of the language. It will group items that it finds by architecture, procedure, function, or package. It does this by adding extra information to the extension field of the tags file.
cz2cz tools is software for converting texts between various charset encodings that are used in the Czech language. The most important feature is autodetection of the most-used encodings (UTF-8, ISO-8859-2, Win-1250, cp850, and Kamenickych). There are both console non-interactive (text-based) and interactive (curses) applications. cz2cz also allows you to convert characters with diacritics to TeX (LaTeX) conventions. The interactive part of cz2cz tools can be used for quick manual complementing of diacritics to texts.
Change is a non-interactive text editor, similar to sed, but much easier to use. It works by substituting a specified target pattern in the source text with another specified text pattern. It can operate on multiple files specified on the command line, or it can operate upon stdin/stdout in filter mode.
reversible hexdump is a hexdump/hex2bin-toolkit that dumps to a special readable and reversible hexadecimal byte-dump, where you can not only change bytes, but also insert or delete bytes. It has a flush-switch, where it will output hexbytes for each single char it reads. This is especially useful (imho) for watching output from slow devices (e.g., serial devices like mice). The hex2bin-utility (the reverse-hexdump) not only accepts hexbytes for input, but also double-quoted strings with most of the escape-chars known from C and makes good attempts at undumping even hexdumps with repetition-lines (a "*" on its own line). It's written in ANSI C.