Here are some minor programs that I wrote to practice programming. Some of them can be useful, most of them not.
id3proc [v.0.1, 22.10.2002] - A program for viewing and editing ID3 tags, that are placed at the end of MP3 files. It can be used for editing, adding and listing (as HTML and text) all of the data saved in those tags.
httpd [v.0.1, 12.09.2003] - A tiny HTTP server. Only GET requests are implemented. It reads documents from fixed root directory and has simple HTML directory indexing.
dgtunnel [v.0.1, 28.09.2002] - TCP connection tunnel. It can generate connection log that can be useful if you want to learn how some of the protocols work. See the example.
chat [v.0.1, 10.10.2003] - IRC-like telnet chat server.
pgm2dxf [v.0.1, 07.11.2002] - A program for converting gray bitmap into a mesh of 3D surface. It can be used for turning a photo into a 3D relief. A mesh is returned in the DXF format, so it can be used with 3D processing software. Here you can see some results of using this tool.
plkon [v.0.1.0, 02.11.2001] - Simple script that converts polish characters. It can handle 19 "standards".
LPTint [v.1.0, 27.12.2000] - An Turbo Pascal unit for controlling devices connected to the printer port using the AVT-2027, AVT-2445 and compatible interfaces. It can control stepper motors (with 4 coils). Interface circuits are described in 3/97 and 9/2000 issues of Elektronika dla Wszystkich (polish electronics magazine).
fonts [v.0.1, 11.10.2002] - A set of ISO 8859-2 console fonts. All of them are in PSF 8x16 format.
graph [v.0.1, 31.10.2002] - Graph generator for audio data. Sometimes useful when working with raw sound files. You can see some example graphs made using this utility.
tape [v.0.1, 07.10.2003] - An experiment with storing computer data on audio tapes via soundcard. It can record and read with average speed of 10B/s. It's just an experiment, but maybe you can use it for something practical.