The app store for iPhones and the iPod Touch is not the only source of software for mobiles. Nokia, BlackBerry and Android phones all have their own stores, and even Vodafone is getting in on the act — its new 360 service features downloadable software.

Apple’s virtual turnstiles remain the busiest, with 200m apps downloaded a month. But the world’s second most popular store is not tied into any device or network: users of GetJar’s mobile site (m.getjar.com) are downloading more than 55m free apps worldwide every month — and the most popular include some surprises.

Who would have thought that the second most downloaded app from GetJar by British mobile phone users in October was one that summoned Muslims to prayer? Once Azan has been set to local time, a digital muezzin will call out from a phone five times a day. About 3m copies have been installed to date. Another Islamic app, Al Azkar, is also in the UK’s download top 10; it displays Arabic prayers. Like the recent news that the most popular boys’ name in London is Muhammad and variants, it’s evidence of the UK’s growing muticulturalism.

GetJar’s other most requested apps reflect the more expected preoccupations of mobile users: sending messages and hanging around on social networks. Facebook Mobile (which allows users to update their profiles on the move), Nimbuzz and eBuddy (instant messaging and chat over the internet) are the all-time UK top three GetJar downloads.

Today’s expensive smartphones come with similar social networking software already installed, but GetJar’s target market is very different. It is primarily used by people with second-tier handsets — the cutting-edge phones from just a few years ago that can still be picked up cheaply, or are now sold in developing nations (GetJar’s two biggest markets are Indonesia and India). Navigate to the site and it asks you which handset you are using, then only displays relevant apps. With half a billion downloads to date, that makes it a simple way for the whole world to join in the app revolution.

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