Spiral Synth is a physically modelled polyphonic analogue synthesizer. It is capable of creating the kind of sounds made by hardware analogue synths, the noises used in electronic music. You can also use it to make stranger sounds too. MIDI is supported, and it uses the standard OSS/Free sound output (/dev/dsp).
Sizzle is a Scheme interpreter for embedding into C applications and for standalone scripting. It implements a nearly complete subset of R5RS Scheme, adding a lot of primitives for U*ix scripting, regular expression searching, a simple module system, dynamic library linking, powerful string processing procedures, and much more. It includes a user's guide and an embedding manual in texinfo format, some examples, the embedding library, and a standalone interpreter for interactive use and scripting.
popexec is a program for Unix/Linux which checks a POP e-mail account and then runs a program whenever new e-mail arrives. It can also optionally run a program when it sees that you no longer have new e-mail in your POP box. Examples are included which show you how to: Write "You have mail" or "You have X new messages" to a terminal, make a terminal beep, play an audio file, pop an X window onto the screen, make your keyboard LEDs blink, change your desktop background.
pftp allows you to send and receive files and directories recursively, send and receive standard input and ouput, filter your connection, set the net buffer size, set the bandwidth, send UDP datagrams unicasted, broadcasted, and multicasted (which is meant for AUDIO and VIDEO streaming), send data to another user and manage that data, perform a network test based on either UDP or TCP, and use optimized buffers for your Gigabit Ethernet links. pftp can start from command line, as a daemon, or by inetd. All features are supported for IPv4 and IPv6.