I personally use Rescue Time
But I believe that these are good tools as well:
It helps you keep track of your projects as you are doing them.
Also Toggl is a time tracker that allows you to easily keep track of what you are doing as you are doing (like keeping time sheets for clients)
This tool will track the time you spend on each project: myhours
the way to make this (or any of these) most effective is to assign each project to a client, so you can see how much time you spend on each clients’ projects, then add in the money you are paid for that project to determine effectiveness.
And you can also see how much time you are spending on each of your own projects (so keep track of email writing, article writing, ebook writing, etc., separately and get a print out at the end of the week)
For more ideas of tools, read this: ideas for tools