Arkos Tracker
Arkos Tracker is a music and sound effect composing tool that runs on a PC or Mac (i.e. it is not a CPC tool), but which can be used to create tunes for Amstrad, MSX and Spectrum computers.
Arkos Tracker and it's tools are built using the .NET framework. To run it under Linux, you need to install mono and libmono-winforms2.0-cli. Then you can run them with "mono <filename>" e.g. "mono ArkosTracker.exe".