With PayPal you can send money to any email address. If that address isn't associated with a PayPal account an email is sent telling the recipient to sign up to PayPal and claim their money. [1]

I don't see why giftdish couldn't work the same way: you send your gift to an email address and the recipient then has to open account to claim their gift if they don't have one already. Having a gift waiting would be a pretty strong incentive to open a new account.

[1] - https://www.paypal.com/webapps/helpcenter/article/?articleID...