Source codes

C/C++

chamOS - Trivial operating system

quark - A simple, line-oriented text editor

Foo - An esoteric programming language

nullcipher - Null-cipher

asdf - Something like grep

prshd and prsh - Primitive remote shell

tcptoe - Tic-tac-toe server for *nix

filecrypt - File encryption (XOR)

Morse code - Beep-beep-beep

pwdchk - Checks password strength

Vigenère cipher - More complex substitution

ROT-n - Simple substitution

Alarm decode - Alarm decoding game

Perl

MD5/SHA1 dictionary attack - Using Digest modules

IP Scanner 0.2 - Simple, with some options

Visual Basic

Lightspeed IP Scanner - Multi-threaded scanner

SpyMaster 1.3.5 - Remote administration tool (RAT)

BlackEye v1.6 - Keylogger with some extra stuff