In my daily work as a web designer and educator I use a few apps to help me stay in the loop. Whether it is keeping track of projects and billing, doing a presentation or getting files from my local computer, these are some of the apps that I use.
Since I use the Daylite application on the Mac, I use Daylite Touch on my iPhone. This is all project and customer relationship management (CRM) based. Daylite keeps notes and informations on all projects and leads (opportunities) that I have going on and shows me the exact status of them as well as stores tasks and appointments in the Daylite calendar.
The application itself is free from the App Store but requires a Daylite Touch license to work from Marketcircle and requires syncing with the computer application.
Most payments into my company are done through PayPal and being able to check my account status from anywhere on the iPhone is a big plus for me. Even though I rarely use it for transactions itself, you can both request and send money through the app.
PayPal is available for free on the App Store.