I can't say I've used it, but if you're looking for time tracking, check out Harvest: http://www.getharvest.com/ It has time tracking that you can convert over to timesheets. You can also track expenses with it. It has a mobile app for when you're in the field. What I like about it is that it uses elapsed time and allows you to bounce back and forth between items, rather than having to make multiple entries per day. I currently use Harvest, and it's allowed me to capture billable time much more easily than with other methods. It's extensible with add-ons for Basecamp, Asana, Chrome, and more. For some companies, it can even handle invoicing.