O2 has announced that it's launching a scheme called O2 Money, to help you keep track of your finances using your mobile phone. The network has partnered with Natwest to offer "Load and Go" and "Cash Manager" pre-paid Visa cards.

Both cards are offered free and only available to O2 customers. They send you text updates whenever you spend money on them, and the pre-paid nature means that you can only spend cash that you've already waved goodbye to from your bank balance.

The Cash Manager card, the company says, is designed for people who "want to keep their disposable income separate from regular outgoings". It gets loaded up online, works like a debit card, and it doesn't cost anything to withdraw cash from, unless you're using one of those dodgy cash machines that charges a fortune.

Then there's the Load and Go card, which is targeted at kids aged 13 and up. Parents can load it up online or at "one of over 20,000 locations across the UK". It won't work in places like online gambling sites, but does have chip and pin security, so that your kid won't have to worry so much about losing cash.

Both cards will be available from the O2 Money website from the middle of August.