I have a simple question.
What are the most popular/useful sensors and shields on the market for Arduino (mainly sensors)?
For sensors, I mean anything that receive an input from the environment, ie. Accelerometeres, compass, gas, light, barometric, etc
And for shields, just basically any shield for the arduino, ie. motor shield, lcd, XBee, etc
As for popular, it can come from your own viewpoint or the general market's view point.
For example, I currently have an accelerometer and digital compass, but in my opinion, the MPU6050 is most useful.
This is just a general market research question. I hope I posted in the right section, as I can't really find any other suitable section to post in.