If you are feeling nostalgic for Top of the Pops, you can always catch vintage reruns on BBC4. But if your musical tastes are a little more contemporary, you can relive the magic of the top 40 rundown with the O2 Tracks service.You might have noticed the name 'O2' in there, but not that this isn't limited to just O2 users. But if you are on that network, you will get it a little cheaper.Get what you ask? Well, get the top 40 on your phone, syncing songs overnight so you'll always be bang up to date with what's hot and what's not. Apart from the top 40, O2 Tracks also throws in an app cast from Radio 1 DJ Scott Mills, plus 'celebrity gossip'. But don't let the latter put you off.The app (which syncs online, but is available to listen to offline) is initially available for Android and iOS users, with BlackBerry and Windows Phone apps to follow. It's also free for two months if you are an O2 customer, after which you'll be looking at £1 on top of your monthly mobile bill. If you are not an O2 customer, it's up for a far more pricey £4.99 per month.