For me: the GTD tracks app can help manage all the stuff that needs to get done - for work & home; while a custom timer/billing app keeps tracks of hours worked

For me: the GTD tracks app can help manage all the stuff that needs to get done - for work & home; while a custom timer/billing app keeps tracks of hours worked - a glorified timer app that summarises billable hours and generates invoices http://www.getontracks.org/ http://www.getontracks.org/