Paydivvy

Paydivvy is a group payment service that helps you pay bills and collect funds from multiple people. Technically you could just send it to anyone after it's collected, but the service offers quick and easy payments to over 5,000 merchants.

It's free to use unless you pay with a credit or debit card and the interface is really nice. That means you can pay bills to service providers and friends at no charge so long as you transfer the funds via your bank account. Overall its a really decent service and definitely the most inexpensive way to send money to people, even if you don't use the group collection features it offers. As for downsides, it only works in the US and the only way to receive funds is to transfer it to your bank account—which is what most people would probably do anyway, so it's not that much of a downside.

 I've also looked at WePay before and thought it was a pretty clever option, but Paydivvy seems to be a bit less-expensive and provides better bill payment options. If you're just trying to collect funds in a group pool, though, WePay can get the job done well.