From the same people who brought CCleaner, here’s Defraggler. I’ve not tried it personally yet, but I need to get it down here before I lose it again. (I often lose links, so its one of the purposes of this site.)
It’s free, compact, and it allows single file defrag. Sometimes its just that one big file that you load often, and you want it fast. So this is a program I’ve dreamed of.