We highly recommend that new parents keep a journal during baby's first years. Not only is it fun to look back on the journal in later years but the journal will be a valuable resource recording important information such as medical history.
For the first year or so record important milestones, doctor visits and your observations/feelings. As your child grows you can record the cute or funny things that they say or do.
It's fun to look back on the journal as your kids grow/get older. Bring out the journal during family dinners when your children are older - they love to hear the funny stories about themselves and the things they said or did!
Setting aside a few minutes in a week to write in the journal is time well spent and you will be glad you captured those important and fun events.