In a collaborative job, especially one that lasts a long time, it is not uncommon to run into a situation where you need to track down when a feature was changed and by who. Just yesterday, I was checking an assembly and noticed that the stock used was not what I expected; I needed to track down who defined it and when it had been done, so I could find out why it was the way it was and root out what else might be effected by the change. Checking who last touched the file wouldn't be enough, because lots of other stuff had been done to this stock over weeks of work.
RMB click a sketch or feature>choose feature properties, and down at the bottom you will get an accounting of when the feature was created, who created it, and when it was last changed. I wish I could also find out who last changed it, but the 'last changed' date was enough - I could check against time sheets to see who was working on the job on that date, and ask him why the change had been made.
Of course, this information (that is already in every SW file!) would make for a killer macro: it sure would be swell if someone could press a button and find out what had been worked on over a time period. I could interrogate a model and find out what had happened to it while I was on vacation, use it to evaluate how productive any of our guys is in a day, check workflow on an earlier job to help understand how to quote the next one, or even check the model a few days later and find out what I worked on to confirm the accuracy of my timesheet.