Launching Next has discovered 6 recurring billing startups.
Subbly
We make it easy to start a subscription business
Liquid Payment
Recurring Billing & Payment
ZBillingNET
Free ASP.NET Billing Software
PayWhirl
Create Membership Clubs in Minutes
ChargeBee (BubblePath Inc.,)
Subscription Management & Recurring Billing for Online Businesses
The Complete Client Management, Recurring Billing & Support Solution
WHMCS is an all-in-one client management, billing & support solution for online businesses. Handling everything from signup to termination, WHMCS is||http://www.whmcs.com