I think Ode or Apollo (still haven't read the latter) would make great gifts because they are single volumes. Surprised by the sort of luke-warm reaction to Ode, I really think it is an absolutely incredible work that I've almost insisted a lot of my friends purchase.
Edit: Oh c'mon, be a jerk. Give someone that volume of Berserk where the Eclipse happens and everyone is eaten (and/or 'fertilized'
) by demons. Man, can't wait to see the gift they'll give you in return...