I've personally been using RescueTimefor a long time now. The Premium version is based on a subscription (monthly or annually), so it may not fit your need, but there is also a free version, which is enough in my case. The data is collected automatically from a Desktop application, the dashboard and settings are web-based.
I used TimeSink which is a Mac application available on the Mac App Store. It is a "buy once" application, cheap, light, but does not have so many features. I like the way activity is displayed: every application has its own timeline, so you can really keep track of your day.
I also used Time Track Pro for some time. I like the way data is displayed with vertical stacks. The Application is cheap, light, and available on the AppStore, but it hasn't been updated in a while.
Finally there is Timing, also available on the M.A.S.
