(Not sure if any Android developers are still on this forum, but...)
On the screen that confirms that you have sent money (if there is one), it would be useful to see the current updated balance of the address you send the money to. Not sure how it would be implemented (Connected to blockexplorer.com? Pulled directly from network communications?). The reason I believe this will be useful is if, say, a restaurant brings out a bill with a QR code to a table with a lot of people without splitting the bill, each person paying will be able to easily keep track how much has been paid to that address, and how much is still left to pay. A network-based confirmation of payment receipt would also be useful for the payer other situations as well.