Time Tracking is definitely the most important aspect for small and medium sized businesses for better and easy project and task management. Hence, we had been using Replicon's simple to use cloud based time tracking software - http://www.replicon.com/time-tracking-softwares.aspx

It is just too quick to implement and has got nice features too such as calendar view interface and completely hassle free experience that can be accessed from anywhere, being a cloud based application.