While I don't have any name ideas for the competition (yet! I might think of something), I do really like the idea of debit cards. Carrying around coins is such a pain and having to visit the bank less often is a good thing, especially with the strikes going on currently. The only problem could be with not knowing how much is left in your account if you're not physically going to your vault to check but I think that could be easily solved by a monthly flown message or owl telling you your account balance. If these cards work, I think they could easily be my favourite wizarding technology.