Zoho Projects also has "Timesheet" tab in which project users can add their work log hours daily.

User can use the start / stop clock feature to automatically log the hours in their respective timesheets. Under "Tasks & Milestones" tab all the tasks of the project will be displayed. Next to the task assigned to that particular user a green clock icon will be displayed.

User can click to start the clock and can the clock again to stop the clock. Once the clock stops an entry in timesheet for that task will be automatically added by calculating the difference between the start time and end time as the hours spent on that task.

Screenshots will help my explanation better.

Green start clock will be displayed only for tasks owned by that user

Click on the Green clock to start your timer

Once the clock ticks, red clock icon and another clock icon gets displayed next to that task

You can click on the red clock to stop the timer. You can mouse over on the display clock to know the time spent on the task

After clicking the stop clock, timesheet entry is added automatically by calcuating the difference between start and end time as the hours spent on that task

checkout the damn cool feature @ http://projects.zoho.com

Prince