Just copied and pasted this from The Guardian
Azimo
Works on: iPhone and Android
Cost: Free
Azimo lets people transfer money from the UK to more than 100 countries at a fraction of the rates charged by banks or money transfer services.
To send money, users need to register and enter the recipient's bank account details. Azimo charges about 1% of the value of the transaction, up to a maximum of £15 per transaction.
The app claims big savings versus other money transfer methods. For example, sending £500 from the UK to Poland would cost £42.50 at a typical high street bank, £20.90 with Western Union, or £19.70 through PayPal. Amizo would set you back just £6.25.
Most banks and mobile phone networks have developed mobile money apps, most of which work across all networks. It's also worth considering O2 Wallet and Barclays' Pingit. Both are free and open to anyone.