I use Freckle to track my time. Hands down it is the best $12 I spend every month. It's easy to use. The weekly reports I create (see below) have helped me reach my hourly goals. It's made invoicing almost, dare I say it, fun. AND it's pretty to look at.
Plus. Yes, there is more! Freckle has this great view called Pulse. This view (see below) shows me a month at a time with great little pie charts on each day. The charts visually show me how I am using my time. The bigger the chart the more time I've worked that day. And then each project I worked on that day is shown by a piece of the pie. I use this information to delegate certain days for different kinds of work once I see a pattern form.
I love Freckle. And, if you are in need of time tracking software, I think you might too.