I use Rachota since 2004 when I started to work from home 3 days a week and I wanted to show my boss what I was working on and for how long, when etc. Rachota helped me not only track projects but its real benefit are the analytic features showing time utilization, ability to look back and investigate measured data. Rachota also provides suggestions on better time efficiency!
Rachota received many positive reviews over the years which logically resulted in permanent Wikipedia entry:
http://en.wikipedia.org/wiki/Rachota_Timetracker