Astro-Bill is an iPhone app for time billing and expense tracking. You can organise your billable hours or items for each job you work on, and can sort the time by categories which you define. Astro-Bill comes pre-loaded with categories for Architects and Astronomers and it is easy to create your own set of categories. Astro-Bill supports billing in multiple currencies, and different tax rates for different categories of work. You can create invoices as you work, at the end of a job, or on a monthly basis. Invoices can be sent by email to yourself or clients. You can also export your billing data by email for saving in another application.