A lovely idea which I've since used is the baby coin sets you get from the Australian mint. So you buy the one for the year the baby was born and it's a keepsake. They have all the coins for that year in a nice slip folder thing with a baby theme, like Blinky Bill and space for date of birth, time etc. They're about the $30-$40 mark. I had to buy one from 2009 for my son, cause we missed his, and it is now $90! so while it's a keepsake, it's also valuable as time goes on.
Other ideas are the Hallmark storybooks that Mum or Dad can record their voice onto, so the child can hear Mum read the story. Something the child can use is always good too, like baby plate sets or a special soft toy.