For Windows:

http://www.adrc.com/software/data_recovery_tools/
http://www.piriform.com/recuva
http://www.pcinspector.de/Sites/file_recovery/info.htm?language=1
http://www.free-av.com/en/tools/10/avira_unerase_personal.html
http://paradiseprogramming.tripod.com/flopshow.html