Hello!
If you use a laptop (like 99% of the freelancers do) and you don't want headaches I would recommend you stay away from the Odesk time tracking app.
It crashes A LOT and it will make you pull your hair out and work for free for your customers. It crashes and does not notify you, so you keep working and 3 hours later when you check - 0 time logged!
3 weeks later - still working with their support to find a solution - on my time! And money!
:( very disappointing
Adriana