The mobile games industry can be a bit navel-gazey, but sometimes it's important to look outside, to see what the relevant trends are in related markets.

So, check out this story on music industry blog Coolfer.

It concerns the special offers on Amazon's MP3 Store in the US, and explains how dropping the price of The Aphex Twin's 'Classics' album to $1.99 for a day sent it to second spot in the site's MP3 album chart.

In fact, on the day Coolfer checked, the top eight albums in the chart were all on special offer, and even unknown artists are benefitting from their albums being dropped to the $1.99 price point temporarily.

And the relevance to mobile games is...?

Check out the iPhone App Store, where the £5.99 releases of Sega and Vivendi are jostling up against the £0.59 Air Hockey and £1.79 TanZen.

Or look at how Gameloft decided to slash its prices after just a week on the App Store competing against cheap or even free rivals.

There's strong evidence that there is a digital 'sweet spot' under the £2.50 mark (it's traditional to refer to this in the UK as 'the price of a pint', depending on how posh your local boozer is).

Does that mean all games should be sold for less than this price? Probably not - Super Monkey Ball quickly shifted more than 300,000 iPhone downloads at its £5.99 price point.

But the experience of Amazon's MP3 Store - and trends so far in the iTunes App Store - indicates that even temporary price promotions are an increasingly powerful tool in the hands of anyone selling digital content.