Arduino & Raspberry Pi
http://www.scratchmypi.co.uk

https://github.com/search?utf8=%E2%9C%93&q=amateur+radio&type=
http://www.dxzone.com/9-amazing-arduino-ham-radio-projects/
http://www.elekitsorparts.com/product/funtronics-k3ng-keyer-fk-10-99-winkey-emulation