Over5 is a program for transferring between c64/vic20 machines and Amiga/PC/UNIX boxes. It supports serial transfer at 38400 bps using only a RS-232 level converter and a 3-line standard nullmodem cable. No special serialport chips are needed. Source code is included. It features read/write/execute memory, filecopy with wildcards, read/write raw disk, read/write ZIPCODE archive, the ability to use the Amiga/PC/UNIX box as a harddisk server ($0801-$f600), builtin diskturbo, and a fast basic bootstrap for most cbm 8-bitters.
sr-convert is a sample-rate conversion utility for WAV files. It supports a wide variety of sampling rates and can convert from any of the supported rates to any other. It runs under either x86 Linux or Windows and uses SSE instructions if they are available. Great pains have been taken to make sure that the sound quality of the conversion is excellent.