+1 on this one as well. I built a shell-based one that pipes out to Google Calendar [0] and then started using Toggl [1]. Toggl works best since it's mobile and web, and they sync with each other, but it's still not totally great from a UI/UX perspective. Timely [2] is beautiful, but doesn't have actual time-of-day data, which I'd like.

Nowadays, I simply plan out my day in my calendar, adjust as necessary, and take that as the data. I don't get to do any crunching of the data like I used to (like graphs and quantitative analysis of where my time is going), but it does serve the purpose of making me aware of what exactly I did during the day.

I'm working on something that will do this quantified-self-esque time tracking built specifically for QS (instead of for freelancers) when I have free time, because this awareness of how I spend my days has quite literally changed my life.

[0] https://github.com/markbao/vestige [1] http://toggl.com [2] http://timelyapp.com

Rescue Time is good. Not sure about UI though!