I created an app that would poll my transaction data from my bank's website and then send push messages to my phone if any new transaction comes in. I loved it. While doing groceries, having not left the line and packing up my goods, I'd get a push message of the transaction. This gave me a real feel for what happened on my bankaccount.

When notifo stopped (free API to send push messages without having to write your own native app); I didn't re-implement it, but from time to time, I wished I did; maybe something I should look into again.