>>>Maybe you should update the screen in steps to make it smooth
>>>
>>>

>>>for( x = oldPosition; x <= newPosition; x += 0.5 ) // degrees  ( or less than 0.5)
>>>   updateScreen();
>>>

>>
>>Hmm. The events come in fast enough - in fact, as in previous reply, I'm taking the opposite approach to *reduce* the number of screen updates (which draws an arrow on HTML5 Canvas)
>
>

>The Nexus has a gyroscope ? Try this http://www.sundh.com/blog/2011/09/stabalize-compass-of-iphone-with-gyroscope/

I believe the deviceorientation event must supply data using both the gyroscope and compass. IAC it's the only HTML5 API method of accessing the information.
But the device calibration (based on looking at an app such as 'Micro Spirit Level') is good.

I should also probably clarify what I meant by 'flick':

When rotating the device smoothly on a flat service the reading will increment smoothly to a certain point then jump a seemingly random amount (maybe 30 degrees, maybe more). Reversing the rotation direction slightly will then cause it to jump back by the same amount.