Sensor apps

there are many apps out there that utilize smartphone sensors to do some cool stuff... like monitoring your heartrate or using it as an emf reader to detect ghosts:D..... well i have heard that there are many more things these sensors can be used for... so i want to know about apps that utilize the sensors for some other cool stuff other than the two i mentioned... i have sgs2

Bubble Level


Lux Meter



Noise Level measurement (Decibel meter)

Range finder (Distance measurement)

oh yes...i also have the compass app... are there anymore? as i heard that there are pretty cool applications for such sensors...

For what purpose you want to use the sensor app?