What programming languages and tools can you use with Arduino?

Arduino is a powerful platform with great software in the IDE, but should you want to broaden your horizons and try something different to program in, here are a few suggestions (note: Ardusat doesn’t officially support any software besides the IDE, these options are for intermediate users) :

ArduBlock

Snap4Arduino

CodeBender

Minibloq

Modkit

Arduino IDE for Atmel Studio – Atmel Studio

C#

Python

LabVIEW

Cycling74

Which alternative Arduino tools have you used?