mems accelerometer

can you please tell me how does a mems accelerometer work and some good companies which manufacture them

As for companies, Analog Devices, Motorola (now called FreeScale) and ST Microelectronics make accelerometer chips.

Thank you so much. but can i know how exactly it works, from the data sheets i only came to know about the I2C SPI interfacing etc, but i don't know how it works like if i place it on my hands and move my hand up and down will there be any sensing action or if i place it on a finger and move only my finger up and down with hand remaining constant will there be any sensing action. Brother please help me i want to know this :-[

A quick web search turned up this page:

http://www.sensorland.com/HowPage023.html