Two feature suggestions:
1. Some audible indication if you receive bitcoins. Andreas Schilbach's wallet has a very neat 'tinkling coins' sound. Just something subtle. Would be a great addition in the user experience, I think (sounds crazy, but often I've heard "damn I love that sound of incoming coins!")
We keep getting asked this, and we keep having to explain that this is terrible for privacy. The only way a wallet can know that you have received coins is to constantly keep asking a node for an address babalce. Whoever runs that more then knows that that's your address. And with HD you would be pinging multiple addresses, so the node will know they all belong to you, and will be able to piece together your entire transaction history.
Sorry for my ignorance, but isn't this more general than playing a sound. Presumably, you want to update the wallet balance from time to time anyway. Don't you have the same address pinging privacy problem no matter whether or not you play a jingle? I don't understand the connection to the audio file.