We needed a way to keep track of the time we spend on each project, something as simple as pressing a button and starting the clock. So, we came across this free app, installed it, and configured it to meet our needs. It will automatically link to our accounts and opportunities.American Data Company Timer
This is a free App available on the Salesforce AppExchange.
The customization guide helps to configure the timer so it links to my Projects. I'm also able to specify the billing type, weather it's consulting, non-billable, documentation, etc. This way, I can keep track of all the time I spend with a client and measure where my time is being spent.