For a limited-time, Google is willing to pay people to invite their friends to use Wallet. The tech giant will provide you and the recipient with $5 in credit whenever a friend who doesn't already have a Google Wallet balance receives money from you. Any amount is fine, including as little as a penny. All that matters is that you both live in the US and that they don't already have an account.
[Free Money] Google Will Give You And Every New User You Send Money To Through Google Wallet (In The US) $5 For A Limited Time was written by the awesome team at Android Police.