This would be an excellent addition to the service.
Ability to log spent time to an issue, or just spent time in general, like time designing or researching etc... for a date.
Maybe ability to add time to an issue via push? i.e.
#12, time #1h blablabla; //fixes issue #12 and add 1 hour to it
#12, time #25m blablabla; //just add a comment to issue 12 and add 25minutes to it's spent time;