Edit: This is a standard .JAR file and can run on anything with Java - Not just Droid (won't run on iOS).

This is a GREAT piece of code. I use it on Windows and OSX all the time.
When I'm ready to do a large print, or a commission ($$) print, I will run their STL through Netfabb to ensure it is clean and working, then send it via GcodeSim to get a more accurate time (or close estimate) and you can also use the top and side views to see if all parts have printed correctly - I had problems with my i3 dual extruder not printing filament paths for 2 days until I realised!