Yes -- books are always a great gift. You can never have too many.
They end up in the house, the car, the diaper bag, etc.
Some that my kids loved when they were little --
Any of the Dr. Seuss classics -- Go Dog Go, Green Eggs and Ham, etc.
Corduroy series (there is a great set of board books that we loved)
the Max and Ruby series by Rosemary Wells
anything by Sandra Boynton
There are so many good ones. I love the board books because the little ones can turn the pages themselves without ripping them, plus they can stand up to mouthing, being thrown, etc.
Clothes are great, too, but sometimes it is hard to get the correct size because the little buggers grow so fast!!
If you go that route, ask the parents for a brand name they like and the correct size in that brand. Sizes vary tremendously by brand!