Zoho Invoice - 100% free online invoicing software for small businesses.
Invoice At Once - Easy Invoice creation.
Bill.com - Bill.com provides ACH payments processing, automates your accounts payable and accounts receivable processes.
INV24 - INV24 is a free online invoicing and accounting software.
Slimvoice - Insanely simple invoicing
Simple Invoices - Never Wait For Clients To Pay You Again!