There are a lot of solutions out there for tracking your work time on the web. I did some hunting around recently, and typical pricing for multi-user accounts was in the $20 or more per month range. If that’s too rich for your blood, you might want to take a look at new entrant TrackMyPeople – who are free while in beta (and possibly afterwards; they haven’t committed one way or the other yet).
TrackMyPeople offers direct time entry, online timers, or time-entry widgets for Windows or Linux (an OS X widget is promised soon). It’s especially strong in reporting, offering multiple views of your cumulated time over various time periods, including fancy graphs. There are a few rough edges in the current beta, but nothing that makes it unusable.