An idea a day: 69. Allow users to use phone/cell phone and credit/EPS card to reload Octopus card, anytime, anywhere. Apart from AAVS, it provide users with a convenient way to recharge their card once in need. It can also let you to add value for your friends, who may not have any credit cards/EPS in the moment, and can't find any shops/MTR station nearby. It could also act like personal ATM machine for cash, if there isnt any.
For 3G phone with a web-interface, the transaction can just like any online merchandise, settle the deal with credit cards. For 2G phones, users can enter the card numbers in a specific sequence, guided by a sound navigation. Apart from using credit card, EPS cards could also be used, just like picking $$ from ATM machines.
As every Octopus card has its' identity, by entering the numbers into your phone, specific card can be reloaded.