Meaningul Christmas gift for a 6-7 month old?

Our son is 6 months old and will be almost 7 months by Christmas. We have very little money, I'm working part time and I don't want to load him up with a bunch of toys. Both sets of grandparents are going to spoil him rotten for Christmas so I want to get him ONE meaningul gift that we eventually put away for when he is older to mark his 1st Christmas. We already got the 1st Christmas ornament at the baby shower this summer. I suppose I could buy my own but any other suggestions?