Sorth Timewerks (Ipod/Iphone)

The premise is simple:

Set up your client details (can just pull them from the Contacts)
Set up various jobs or projects for those clients
Set up your flat rate Products and or Services
Set up your hourly rate

Essentially it comes down to this:
When you walk into the client, and start a job, you select the client and project you are working on, and simply start the timer. The timer will run in the background and you can listen to music, use the calculators, etc etc. It will not influence the timer. If you go on a coffee break, or if somebody starts chatting to you about your weekend or some other non-project related issues, simply pause the timer, and start it up again when you start the work again.

When you are done. Stop the timer and add it as “Hours” to your project.

At this point you can also add various flat rate products to the project. So if you were on a shoot, for instance, then your hourly rate can be added as a pre-quoted rate for the day (no need to run the timer) but now you can add the equipment used (i.e.. your camera bodies, light-meter, studio lights, model fees, assistant fees, travel, etc, etc) as soon as it’s done. Simply create an e-mail right from the app which contains the full breakdown of the invoice, with all the details, and send it next time your iPod is on a wifi connection or straight away if you are on an Iphone.

You also have the option to select the items you are invoicing for on a given day, or let them just heap up and invoice at month end. Just depends on you and the project.

When the Client pays, just fill in the details and the app will automagically show you which accounts are still outstanding with the option then to resend the invoice.

This is an awesome little app, and well worth the asking price of $9.99 (but if you only starting out or have very few clients, simply use the free version, available on the Apple AppStore)

When I work in billable hours, I usually work with a start/stop timer on the side (basically the same as the app). The thing this really quickly shows you is how much time gets wasted. You can be with the client for 4 hours but only bill for about 1h20 because of interruptions and non-project related queries you entertain.

The feature list from the Client:

Track multiple projects and clients.
Quickly and easily add timesheet hours and capture notes for each project task.
Time your work for each project via a built-in stopwatch (Task Timer)— each running timer keeps tracking even if the application is closed.
Track and invoice billable items, materials and expenses.
Customize different rates for different types of tasks or items.
Select unbilled items and create invoices directly from your device.
Calculate sales tax as a percentage of an invoice sub-total.
Email HTML-formatted invoices.
Accept credit card payments via integration with Credit Card Terminal (sold separately by Inner Fence).
Create client records from new or existing Address Book (Contacts) records.
Support multiple currencies.
Export your data to tab-delimited text files via a wi-fi connection and a standard web browser.
No network connection needed to enter and view data— all records are stored locally on the device.