I am listing the apps I have looked at so far. I must emphasize that none of them really solves the problem stated above perfectly.
Here's what I have looked at so far based on my google doc list
- On the Job looks great, but the developer seems to have abandoned it. At least he does not really fix bugs and is very slow to respond to his user base.
- Timings light-weight but the UI to create clients, projects and tasks can be confusing. I am testing it right now. A friend uses it and says it crashes sometimes though it has not happended to me yet.
- Harvest looks good, it does have a desktop client itself and an API that is used by lots of apps. But it is subscription-only which is a no-go for me and costs at least $12 per month.
- The same goes for Toggl: looks good, but is subscription-based and constscosts $5 per month
- iBiz and timeEdition have been discontinued
- Klok is an Adobe Air app. The UI feels weird. Small typography, limited support for keyboard shortcuts and complex interface.
- OfficeTime feels like the best match so far but the UI is very cluttered (see this screenshot of the Generate Bill dialog as an example). It feels a bit like a Windows app that has been ported to Mac but I am not sure if that's true.
- Timecop is a very minimal approach. There is no way to test it without paying the $6.99 price. Has not been updated for 9 months, twitter account has been inactive for 5 months.
- Tictoc seems very similar to Timecop. No way to test without buying either.