http://anarchy.translocal.jp/radio/micro/howtosimplestTX.html
http://tacashi.tripod.com/elctrncs/smplfmtr/smplfmtr.htm
http://www.scitoys.com/scitoys/scitoys/radio/am_transmitter.html
receivers:
diode between earth and antenna. we listen across the diode:
http://electronics.howstuffworks.com/radio9.htm
also
http://sci-toys.com/scitoys/scitoys/radio/homemade_radio.html
(all radio stuff here is very good but have lost link to other similar home-made caps one)
The Cardboard Variable Capacitor: http://www.crystalradio.net/beginners3/cap.shtml
http://www.mattknox.com/littlelisps.html
and (from incorrect link on that page):
PIC Scheme:
www.iro.umontreal.ca/~feeley/papers/sw03.pdf
Looking for a Z80 Lisp (Bit?):
http://www.iro.umontreal.ca/~dube/