iTunes link: Billings Touch – Free or £8.99 for full version
Billings Touch is the iPhone companion software for Marketcircle's Billings application on the Mac. It’s basically a professional invoicing application that allows you to track the amount of time you spend on projects using a timer that can run in the background so it doesn’t interfere with the other apps you run on your phone.
You can then quickly send invoices from your phone to your clients and even set up recurring invoices for clients you regularly do work for. Another neat feature is that the software can alert you to outstanding invoices that are overdue. Extras like adding mileage allowance and expenses are also supported.
If you work freelance on projects and frequently need to bill your work on a time basis then Billings Touch is a great solution.