I also need such a functionality. I often defrag my System- and Program-partition and there is really no need to defrag my download-temp-folder or my system-temp-folder. Also I don't need to defrag my picture-folder.
It would be very nice to have a kind "exclusion/ignore list" that can be feeded with folders, file-types and wildcasts !!!
Also I want to have an option that says wether Defraggler shows up /System-Volume-Information or /RECYCLE files. I don't need to defrag them..
Another feature I would suggest is to memorize the positions of the horizontal splitter. I always have to move the upper splitter down to see all my hard disks
