Each year I have to write a report for each of my grants. Most, if not all agencies require this, and some (NSF comes to mind) can use these to determine whether or not you deserve the next year's money. Many of my colleagues whine about having to do annual reports. Me, not so much. I don't necessarily look forward to the process, but I do find it useful sometimes (aside from the continued funding). Why?
There's nothing like writing a grant report to put into perspective how much (or how little*) you've achieved in a twelve month period.**
* Hopefully not this one.
** The last year has been a good one in the lab.