Something tells me its not a good idea because if you give someone like a $500 dollar Gift certificate that can be used anywhere, the person will shop till they drop, buying all sorts of things like videogames, books, music, clothes, etc. But will they remember who hooked them up with all those things? I received a Barnes and Noble gift certificate and I used it to buy a book. But peep this . . . whenever I read this book or glance at it on my desk I never remember how I got it. I just assume I bought it with my own money. I forget how someone handed me a Gift certificates to buy the book.
This is like a lost in translation kind of problem. The same thing goes for giving money on Christmas.
Now if someone gift wraps a book and gives it to me i'm going to think of that person each time I'm reading that book. Whenever I glance at the book on my desk it will invoke the memory of receiving it from my friend on Christmas. And I will think of that person whenever I read the book.