It's getting easier to pay electronically. While PayPal has been around for a while, most people think of it as a PC-based system using email addresses. Newer services such as Popmoney focus on mobile payments using your payee's mobile phone number.
Ally Bank recently jumped on board with Popmoney, joining a few dozen other banks and credit unions. Several mobile payment services are trying to become the gold standard, and Popmoney's doing a good job of building relationships and recognition.
If you pay somebody with Popmoney, you avoid writing checks and exchanging cash. Just like with PayPal, nobody needs to see anybody else's bank account information. However, at first glance Popmoney seems a bit more refined -- fund transfers to your bank look more seamless, and the service targets heavy mobile phone users. By joining forces with your bank, Popmoney becomes the default option for payments.
Further reading: