Purchasing cards are credit cards issued by corporations to trusted employees. Digital cash requires both customers and merchants to have accounts with the same issuing bank. Hasn't quite caught on yet, but may in the future. Micropayments similar to digital cash but in very small denominations. Has a bright future.
Electronic checks are just like paper but still in the testing phase.
VirtualPIN is a kind of firewall for credit card numbers. First Virtual issues a VirtualPIN and acts as a trusted source to later authenticate it. Seems like much ado about nothing. Digital Wallets provide a further level of security for credit card transactions. CyberCash and Verifone are leading vendors, and Microsoft has patented an anonymous e-wallet system.