Cybermoola is a prepaid account system, which can be funded with prepaid cards or a credit card. CyberSource offer real-time credit card processing and other electronic commerce services. DebitNet DigiGold Digital Silk Road is a proposed payment system for extremely low cost activities such as delivering and routing packets. Downtown Anywhere has a system using account numbers, and personal payment passwords. Ecash is a fully anonymous electronic cash system, using Chaum's blind signatures.
Free tokens are currently available.
There is a further extension to allow small payments, which are aggregated as a single SET transaction. Value can also be transferred to another account holder. New Notions and Techniques, by Yiannis Tsiounis. Electronic Funds Clearinghouse provide payment transmission and intake conduits over the Internet. Here's a quick summary.