I have scan pictures, first size nappy, first shoes, first babygro, hospital wrist band, first socks, a Guinness Book of Records from ds's year of birth.
I keep meaning to cut off a lock of hair as a keepsake. I have all of the Congratulations cards from the birth too, and a piece of paper that dh used to keep track of my contractions - He jotted down all the times 
I have kept my first mother's day card too. I have quite a few baby pics but have yet to put them into an album.
Realistically, I am not going to hand it all over to ds when he grows up! Dh jokes that I am going to be an emotional wreck when he leaves home, as it is.
I am keeping the keepsakes at least!
Well done, with the thread, op - I started a similar one when ds was born and got no response.