We're currently building a desktop based time tracking application for ourselves, later we will release to everyone. Our main goal is to bring us back on track on our personal projects. Also billing solution for our consulting work.
Out of curiosity, have you seen Toggl? We use it at work for time tracking and find it mostly quite good. Would be curious to know what's different about your use case.
This you can still achieve in other apps like toggl or freckle. But they lack the management and we are focusing on the managing part. Once the beta is ready i will send it to you. Happy to get your feedbacks.
peace