I started using Sparrow for email on my iPhone, but it does not support (for very good security reasons) push email notification.
I wanted to see if I could write something that would let me know when I had new email so I could open Sparrow and check it. By hosting it myself on Heroku I wouldn't need to share my email credentials with anyone else, nor forward my email to Boxcar in order to have their email triggered notifications notify me (as suggested by the Sparrow FAQ)
The end result is a simple app that wakes every 30 seconds (configurable) and connects to Gmail looking for unread email that it hasn't seen since it started (for now). If emails are found, a message is sent to the Boxcar account of the email used to connect to Gmail.
Designed to run with Foreman, can easily be deployed to Heroku with a single worker dyno.
heroku create --stack cedar
Setup config params for Gmail and Boxcar
heroku config:add GMAIL_USERNAME="..."
heroku config:add GMAIL_PASSWORD="..."
heroku config:add BOXCAR_KEY="..."
heroku config:add BOXCAR_SECRET="..."
git push heroku master
Start the worker
heroku ps:scale worker=1
Check the logs