Ask HN: Automatic Bitcoin portfolio tracking app?

Unless my google-fu is severely out of whack, I can't find any apps/web app that can:

1) Connect to my Coinbase account 2) Track my holdings and purchases (which are scheduled weekly) 3) Tell me how much overall I've made or lost

Does this app exist? I don't want to record transactions manually. I'm playing with Bitcoin, but because I buy weekly and the price is still changing constantly, it's difficult to actually track how much overall my net profit/loss is.