At the recommendation of Arlo I downloaded a copy of Billings for keeping track of clients, time spent on a project, monies due, etc. The learning curve takes a little getting used to (i.e. Start a New Slip) but once you get the hang of it, it's an incredibly slick app with a great interface for keeping up with this sort of data. The last program of this nature I encountered was Quickbooks some ten years ago and it was nowhere near this easy to use.