A.G.
When I was in the hospital having my second son, a friend of mine kept my older son who was 6.5 at the time. She took him shopping, and instead of buying something for himself, he chose to buy a blanket for his brother. It's still his brother's favorite blanket, and they are 8 and 15 now. They both love that blanket, and I can see the pride in my oldest son's eyes when he sees his brother still holding the blanket when they watch movies together or when he's going to bed.
That being said, maybe you could take him shopping and offer to buy him something and something for him to give his brother (as someone else also mentioned).