I think how you handle reports depends on how often you have to do them. This is the time of year I have to do annual reports for both my dean and my funding agency. There's some overlap between the two, but it's quite a bit of work to pull all of the information together. Most of the information I need has to do with the past, and I keep it as reference material. I do refer to my current projects list for both reports, but not for details; it's more of a prospectus.
I have colleagues whose funding agency requires monthly reports, which is crazy for research: "Postdoc found grad student had performed incorrect calibration of instruments; six months of data now being corrected. Shipment of crucial samples lost by shippers. In despair." Next month:"Results improved after correction of data. Grad student finds all lost samples under postdoc's desk. Deliriously happy."