Repetier-host (Windows, Mac and Linux) : http://www.repetier.com/documentation/repetier-host/
3d editors :
123 Design : http://www.123dapp.com/design
Sketch up : http://www.sketchup.com/
3D print server (for Mac, PC and raspberry pi) :
Repetier server : http://www.repetier.com/repetier-server-download/
3D Printer OS : http://www.3dprinteros.com
Octoprint : http://octoprint.org
Find some 3D model to print :
Thingiverse : https://www.thingiverse.com
Yeggi : http://www.yeggi.com/
Grabcad : https://grabcad.com/
Repair a model before printing :
Netfabb : https://netfabb.azurewebsites.net
3D Hubs (make $ and offer a 3D printing service from home) : https://www.3dhubs.com