Alot depends on what the client wants to see. I use Quickbooks Pro, and when needed, I use the timer. For my clients, I bill them once a week for the time under one heading 'software development services'. If they wan't to see a timesheet, I send it to them. Although, I have yet to be asked to see a timesheet. If a client is happy with the productivity and the deliverables, they ususally don't complain about the time. Of course, if something is going to take an extra-ordinary amount of time, I tell them in advance so as not to be shocked...