citrusdb is the open source customer care and billing software that can be used in many service industries, internet service, subscriptions, consulting, and telecommunications. Provides CRM, Ticketing, Invoicing, and Credit Card Batches.
gcdb is an aesthetically pleasing MySQL/PHPbilling database. It supports Customer, Payment, Invoice, Account, and Trouble Ticket entries. Meant for ISP, Hosting, or general billing.