I like to mix something humorous with something useful, and hope I do actually know a bit about the person. When I don't know them well enough, a bit of research (asking others / attempting to get to know them better) is required before the present hunting can begin.
One example was a mug filled with chocolate and a chocolate monopoly-type game. Yes, this was for a chocolaholic, and no, not for a female. ;)
Have fun finding out!