Metacharge
Metacharge processes real time payment transactions made by consumers for goods and services (both tangible and intangible) over the Internet, by telephone and mail-order.
Built around an advanced payment gateway, the Metacharge service also includes an Internet merchant account (akin to a bank account for credit/debit cards, which is required before a merchant can trade) and a suite of value added services including fraud prevention, ID verification and subscription management.
http://www.metacharge.com/

PayPal
PayPal enables businesses to securely, conveniently and cost-effectively receive payments online. Our network builds on the existing financial infrastructure of bank accounts, debit cards and credit cards to create a global, real-time payment solution. Our product is ideally suited for small businesses, online merchants, individuals and others currently underserved by traditional payment mechanisms. PayPal has 63.8 million member accounts and is accepted in 45 countries worldwide making it an easy and effective way to transact internationally.
https://www.paypal.com/

Norchex
Nochex provides a fully integrated, online merchant account system that enables businesses to accept online payments from any one with a credit or debit card. The system does not require a payment service provider or the websites customers to sign up for a Nochex account. Each Merchant Account is supported by a dedicated, account manager. Seller and personal accounts are also available.
http://www.nochex.com/