Skydeck, the San Mateo, Calif.-based company, which is developing a service that let’s people track their calls and text messages online, said developers have started to use its platform to create new applications. The company wrote on its blog today that the first three applications have been built, using APIs provided by the company. They are: FreshBooks, a Mac Dashboard Widget and Dial2Do. It’s unclear how Skydeck intends on making money on this platform approach, but it is likely to increase adoption of its services, which could lead to paying customers down the road.

—FreshBooks: FreshBooks is using the APIs to expand its online invoicing service. Its customers, including consultants, designers, lawyers and other professionals who bill by the hour, can use the service to track their time when they are using their cell phone. The application can be found here.

—Mac Dashboard Widget: Developer Mick Thompson created a widget for Macs that keeps track of how many minutes you’ve used in the month, much like the toolbar plug-in for Firefox. The Mac widget can be found here.

—Dial2Do: Dial2Do lets you easily call people or dictate emails or text messages to people you contact most often. Dial2Do let’s users upload your contact list from Outlook or Gmail, for instance, but now when you sign up for Dial2Do you can import your 100 highest ranked contacts from Skydeck.