There may be cookies from certain sites... But if he's aware enough to delete the browsing history, I'm willing to bet he's removed any trace of where he's been
You could also get monitoring software, which once installed will e-mail reports to you of what a user has been browsing. EBlaster is one I've heard of, but never used this, or any other, monitoring program.
Someone else may be able to suggest a free program though, as I don't know the best value or the best programs that are out there...